CP Rail 4203, MLW C424 Build & Paint-up

25650bexs- CP-4203-frontright.jpg
Awww yeeah, action red baby.

Prototype History & Details:

As the 60’s rolled around, Canadian Pacific had fully dieselized its operation throughout the 50’s and retired its last steam locomotives in early-mid 1960. It was swarming with first generation diesel locomotives built for passenger, freight, road and local switching, some new but others getting up there in the ages and coming up for replacement. On top of that, newer, more powerful road freight locomotives were being introduced by manufacturers each year, units that could replace older, worn out, lower horsepower units on a 2-for-3 basis. CP sampled new power in the way of one new Alco-designed “Century” series 2400 horsepower C424 built by the Montreal Locomotive Works in 1963 (8300, later renumbered 4200), and two EMD-designed 2250 horsepower GP30’s from GMD London in the same year (8200-01, later renumbered 5000-01).

Follow-up orders came from GMD for 25 of the upgraded 2500 horsepower GP35 model in 1964-1966 numbered 5002-5025 (originally some were 8200’s), and double that from MLW: 50 more C424’s in 1965-1966 numbered 4201-4250.  The GP30, GP35 and C424 all represented early offerings of the “second generation” of diesel locomotives, i.e., the start of more powerful diesel locomotives that replaced earlier aging first-generation diesels that replaced steam. CP got trade-in credit by trading in some of its older diesels on a 1-to-1 basis (various GP7, FP7, F7B, F9B, FA1/2 and FB1/2, and RS3/RS10). Some of the trade-ins had been in wrecks, others were just older models (some sources may indicate new units were “rebuilt from” trade ins, but that’s simply “paper accounting” and not the case – likely the only things reused were the trucks and some other smaller components).

CP Upgrades(!)

In the 1970’s, CP started making a few modifications to their C424’s. Starting in the mid-70’s, they began replacing the stock MLW door latch handles on the long hood doors with EMD-style “knuckle buster” latches (not done on every single door however). They also started experimenting with different air intake arrangements, replacing the one large intake grill behind the cab with four smaller grills, and later Farr air intake filters in slide-in mounts on the outside of the hood over those openings.

Around 1980, both the GP30/35 and C424 groups were included in CP’s 10-year motive power plan – all were to be rebuilt as roadswitcher DRS-class units, as they had been DRF (Diesel Road Freight) units up until that point for regular road freight service. The 2500hp GP35’s were downgraded to 2250hp for improved reliability out of the 567 engine, which was being pushed to the limit by its GP35 iteration. Sidenote: The GP35’s were also noted by repair staff as being more complex to maintain due to extra transition processes (10 stages in a ’35 vs 4 stages on a GP9, which required electricians to spend extra time calibrating), and many mechanics also loathed the many difficult-to-reach DC brushes in the main generator that could be tricky to change.

Upgrades to both groups included rear numberboards, dual rear head lights and class lights, and a rear pilot. All done to allow them to “properly” lead backwards when operating as single units on branchlines with no turning facilities. The ironic part is that the GP30/35’s were originally built with rear numberboards, but had them removed by CP early on. Horns were also relocated from the cab roof to the rear hood around the exhaust hatch area (position could vary).

Both groups of units continued to serve CP into the 1990’s both in branchline and mainline freight service. The C424’s were based out of St. Luc shops (Montreal QC) for maintenance for most of their lives, and mainly operated in eastern Canada (ON, QC, NB, etc), CP’s lines into Vermont and the north-east USA including the former D&H lines. They did stray to the prairies every so often, and when CP’s GP7/9 fleet was being rebuilt into yard units in the 80’s, a certain motive power planner tended to send C424’s out west to help make up for a shortage of 4-axle roadswitcher power (there are photos of them with GP9’s working prairie grain trains. New GP38-2’s were eventually purchased in the 80’s as prairie power). The GP30/35’s moved around home shops over the years: from St. Luc, Toronto, Winnipeg, to finally out west based out of Alyth (Calgary AB) and Coquitlam BC. The last units of both groups were retired in 1998, but some were converted to 1100-series cab control units and 1120-series cab control road slugs.

Rivet Counting Some Details:

CP 4200 (built as 8300 in the roadswitcher series, later renumbered) was an early “Phase 1” C424 with a number of fuel tank and carbody differences. 4201-4250 that followed were later “Phase 3” C424’s with a rounded rear with no numberboards (initially). CN’s order of C424’s were “Phase 3” with the Phase 2 notched rear end for dual-numberboards (note that the phases aren’t official designations, they’re railfan-invented to describe more significant production changes). In addition, CP 4200, 4201-4209 originally had high-mounted headlights on the cab front, thus the flat area at the top of the cab between the numberboards (relocated to the nose in later years). 4210-4232 came from MLW with low-mounted nose headlights but still retained the (blank) flat area, and 4233-4250 were delivered with low-mounted nose headlights and a regular “knife-edge” cab front with no flat area. Earlier units 4213, 4220 and 4228 got in accidents over time, and ended up getting the later “knife edge” cab faces when rebuilt.

The Model – Starting Point

Above: Our donor C424 shell to strip down, modify and repaint, sitting on a “loaner” drive chassis borrowed from another model. While it looks ok, it’s been factory lettered for QGRY (do not want!), is in the later 8″ stripe scheme (no multimark, and too modern!), and is a bit lacking in terms of some details (it can haz moar detailed parts?).

This build started off with an Atlas Classic C424 shell factory painted QGRY (one of the Hobbycraft Canada commissioned ones that were released around 2002), which is a somewhat unpopular roadname making them easy project fodder. The Atlas shell tooling is good, but the detailing is on the generic side: while the basic body details are correct, and it has separate handrails and wire grabs, the models suffer from lack of appropriate horns, plows, pilot ends, side bells, truck details – mostly little bits here and there that add up. Some of the front cab detail is a bit iffy as well, mainly the numberboards (they don’t seem square enough to me) and the class lights being positioned offset instead of centered above the numberboards as they should be.

Since the QGRY units are all ex-CP, the same CP shell tooling was used in production by Atlas (Atlas made both original DRF and rebuilt DRS body styles for CP, but in this case they used the later rebuilt style with dual rear headlights/class lights/numberboard). However, our goal was to make an early DRF-class unit with a smooth rear, so all those extra bits had to be removed and filled, and some other modifications to the pilot ends and cab were needed. Happily, the genetic tooling also worked in our favour: Atlas didn’t do any of the later rebuilt air intake filter modifications on their shells (to model this, one can use MbyE parts or intake decals from Highball on styrene bits), nor did they do the replacement “knuckle-buster” door latches (to model this, one can use Archer AR88136 resin door latch decals, or similar etched parts by Plano).

Dig In:

As always, begin by stripping the model down. Atlas typically doesn’t use much glue in these, so the entire decorated model can be disassembled with ease, with most of the grabs easily removed with needle-nose pliers. The main body parts were given a 1-3 hour soaking in 99% isopropyl alcohol, which combined with some old toothbrush scrubbing removes Atlas paint with ease. The painted handrails can also be carefully stripped in alcohol. After a bit of scrubbing to get most of the leftover paint out of the nooks and crannies, it was time to begin modifications.

Above: our bare shell all stripped and washed, with new sand hatch already added (!).

Rear End

13790bs - CP 4210 painted and 4201 unpainted.jpg
Above: A modified C424 shows off its patched buttocks, next to the rear of one that’s already been modified and painted. All the old lights and numberboards were filled in, patched, and sanded smooth. Single rear light reapplied. Also note the rear cut-out lower pilot areas. This photo was from my earlier builds of two in maroon and grey, but the rear modifications are the same for this one.

The rear class lights, numberboard and headlight inserts were removed from the inside, the rear headlights shaved off, and all the holes all filled in with styrene and styrene rod, given Squadron putty to fill any holes, and sanded smooth. Some grab iron hole re-drilling may be required around those parts, and be sure to leave the square sand hatch below them intact. Once everything was dry, a hole was drilled between the two former headlight openings, and one of the removed headlight housings was glued back on to simulate the single headlight mounted at the rear.

The rear pilot had the bottom half between the steps and below halfway up the coupler pocket fully removed, as CP had this area wide open on their DRF road freight units (later filled with a standard rock pilot when the C424’s and GP35’s were rebuilt as DRS units).

Front Pilot

The front pilot end was modified by carving off of the stock mini-V pilot. A new CP “rock pilot” plow was outfitted on the front only (I’ve used both Miniatures by Eric part P18, or the Bowser part 190-582 cut and spliced wider with about 0.040″ of styrene – I used the latter for this built).  For rebuilt DRS units, you’ll need a plow on both ends and ditch lights on the front only. The stock MU lines, cut levers, and some air lines were left off until the end of the build, after painting.

CP-C424-Cal-Scale Pilot Plow mods.jpgAbove: The “rock pilot” plows CP had varied a bit between GMD and MLW offerings, and Bowsers seems closer to the GMD version. We’re using the Bowser plow part, but splicing it with about 0.040″ of styrene to make it the proper width for the C424’s, and also carving a curved notch in one side for the air lines, as seen on the right photo showing a modified, and an already modified and installed/painted plow.

Front Cab and Other Body/Detail Mods

To do a early unit, the top of the front cab face was sanded flat, thin piece of 0.010″ sheet styrene (sanded thinner too) was cut and glued on to match

13700s - CP 4201 cab filing.jpg

Above: front cab face modifications, with new class light and numberboard gaskets made of wire.

The stock class lights and numberboard housings were also trimmed off (since the numberboards seemed a bit too rounded at the corners, and the class lights were incorrectly offset. New numberboard housings a bit more square were bent from 0.010″ brass wire and glued on. Class light holes were filled, and new ones drilled centered above the front numberboards (the Atlas ones are incorrectly offset to the cab sides for CP units). More 0.010″ wire was bent around a small screwdriver to get the class light gaskets, and they were glued on over the holes.

Holes drilled for windshield wipers above the middles of all front and rear windows. Holes were also drilled on the roof for the Sinclair antenna (Detail Associates part 1802), and the horn (the stock horn hole is in about right). As-delivered CP’s units had M3H’s with the middle bell pointed backwards. Over time many had them re-oriented with the short side bell pointed backward instead, or replaced with newer K3L’s of the same configuration. A Details West AH-268 was used to reflect a unit still equipped with an as-delivered horn, but the Bowser 190-583 M3HR (actually closer to a K3L) and Rapido 102092 diesel horn set (which has some excellent looking M3H’s) are also good options. The stock Atlas cab hole is in about the right place for as-delivered units, but if you’re doing later one, CP relocated the horns to the long hood to reduce cab noise (consult prototype photos for exact unit placement).

Other modifications included:

  • On the side of the cab, the rear cab wind deflector was shaved off each side leaving the front ones.
  • The front and rear cab vents were shortened a touch.
  • The round sand hatch on top of the nose was sliced off and replaced with a square one made from styrene bits.
    A hole was drilled on the right side of the long hood by the engine area, and a Miniatures by Eric B12 side bell was installed.
  • 0.010″ styrene bits were cut and glued to make the sloping “snow shield” intake covers over the front air intakes behind the cab, and installed on both sides on the hood (these were only present on units 4201-4232, and removed when CP modified the air intakes from one large grill into 4 separate smaller intakes in the 1970’s).
  • Wire was bent for the triangular handrail extensions at each end by the drop step, which was mounted into holes drilled in the sides of the end stanchions and painted white/red. As-delivered, CP’s units had a solid handrail and no drop step, but over time units were retrofitted with a drop-step, end chain, and small triangular handrail attached to one of the stanchions.

Above: on the initial 4203 build I used the stock end handrails and drop step that came with the Atlas C424, but on the later 4226 I made some modifications, including replacing the plastic chains at the ends with A-line metal chain (40 links per inch), and scratchbuilt more accurate drop steps and mounts from 0.010″ styrene and thin wire to allow hinging. Also, the angled braces on the two side stanchions were cut off.

IMG_8861bs - CP 4226 drop step.jpg
Above: scratchbuilt working end drop step installed and painted, with extra wire grab iron added on the outside. Also note chain, and triangular handrail extension.

The cab has an interesting story. When I got the shell, the cab sat slightly off on the body, there was some minor damage to the top cab roof overhang at the front, and one of the front window frames was cracked. It was a new “surplus” manufacturer’s shell acquired from a hobby shop (who also had other surplus Atlas RS3 and C424 shells for sale), but I suspect this particular shell took a tumble to the floor at some point in its life, resulting in the damage. The window frame crack was repaired by carefully drilling two holes in the window frame and inserting a piece of steel wire and glue to splice the cracked area together. The cab sat properly when re-adjusted on the body. And, since I had originally earmarked this unit to become a later 4200 with the “knife-edge cab” front, I made repairs to the top cab roof overhang.

I originally got as far as painting the body with a few coats of grey, painting up all the handrails maroon/yellow, and detailing/painting the frame/walkways black before setting it aside (it was going to become a later 4200 in maroon and grey, the third after doing 4210 and 4201 just prior). I got sidetracked with other projects and the shell sat in the projects box for a few years, before the urge to do an action red unit came up. Ideally I wanted to do one of the early 4200’s with a flat front again since Atlas never made that version in CP, and it had to be an earlier 5″ stripe unit. So this shell was reluctantly pulled out, the area of the cab roof that had been fixed was filed flat, and the handrails repainted red and black.

24625.JPGAbove: The future CP 4203 sits uncertain of what colours she will wear, next to completed CP 4201 & 4210 in maroon & grey – two other former QGRY shells given a complete makeover.


The current Atlas Classic chassis is a fine, smooth running choice, and if your unit comes with it you should use it. However as ours was just acquired as a shell, it needed a drive. You’re in luck: older Atlas “Yellow box” C424/C425’s built by Kato in Japan have just a smooth a drive, are in easy and cheap supply, and fit the newer Atlas shells (The older models are informally known as “Atlas Japan”, “Atlas Yellow Box”  or “Atlas Kato” units, versus “Atlas China” or “Atlas Classic” for more recent production runs).

The only real modification required to the older Atlas-Kato drive, since those older shells had body-mounted couplers, is to either body mount them on the newer shell, or build a coupler mount extension on the chassis, which is what we elected to do.

Above: drilling holes in the frame and pieces of brass to make chassis-mounted coupler mounts on the older Atlas-Kato C424/C425 chassis.

Thick brass 0.040″ strip was cut to size into two extensions, and holes were drilled in each for mounting to the chassis. Two holes were then drilled into the chassis ends, and everything was tapped for 2-56 screws. The ends were then fastened with short 2-56 3/16screws , and once everything was lined up and fit snug, coupler pockets were test-fit and another hole was drilled in each brass mount and tapped for a 2-56 screw.

Above: Holes drilled in the frame and brass extensions. The holes in the extensions were drilled a little bit larger to enable minor adjustment.

Above: once tapped for 2-56 screws, the extensions were added and screwed to the frame using short 2-56 screws.

A small styrene mount was then required to be build up at the ends, to get the correct coupler box height.

IMG_5804es-CP-4226-C424- coupler-mount.jpg
Above: In addition to the 0.040″ brass extensions, a small styrene mount about 0.060″ thick was made to get the Kadee coupler boxes to the correct height. Some extra styrene bits were added to act as a “stop” when the coupler boxes are inserted.

25710bes-Atlas-Kato_C424_Chassis_modified.jpgAbove: the modified Atlas-Kato chassis, with end coupler extensions added and some new lighting. Rebuilt fuel tank also added (see next section).

Another modification I made was to the weights, which are hefty, but just sit loose inside the Atlas-Kato shell. I filed the inside tips down a bit so they were level with the stock plastic grey conduct on top of the motor, drilled and tapped, and fastened the weights on with thick styrene bits.


At this point one can make any wiring  changes, add a decoder, better lighting, etc. I added a pair of 3mm sunny white LEDs and 680ohm resistors to each end, just hardwired to the stock lighting system for now. They’re suspended at each end from wire CA glued to the ends of the weight at headlight level. Notches were cut under the front weight to allow room to run the headlights so they didn’t interfere with the gear tower.

Fuel Tank

Since I acquired an Atlas/Kato C425 drive for my CP C424 project, it came with the solid one-piece fuel tank, but needed the proper split fuel tank. There’s a guy on eBay that sells Atlas parts who usually has that sort of thing, but unfortunately no bueno.

No matter, the snap-on one-piece tank sections on the Atlas C425 tank are easily removed for modification. The air tanks were carefully trimmed off the tops (to be mounted to the chassis later), and the fuel tanks were then cut in half. The open ends were filled with styrene and Squadron putty, sanded smooth, and the sliced tank halves glued back on in the proper orientation. Some styrene was used to lengthen the ends and add other bits such as fuel filler detail. Once painted black, it’ll all look nice and clean under the unit.

Above: The old fuel tank bits sliced up and re-assembled, awaiting a coat of black paint.

Trucks Sideframes

Most of CP’s MLW locomotives delivered during this era had SKF roller bearings, and small axle generators for the wheel-slip system on each axle on one side. The stock Atlas slideframes have the old stock slope bearing caps, that some CP C424 units got from older power when axles were swapped around. So, we’re going to re-equip this unit properly.

One nice bonus with the Bowser C630M’s is they came with a full set of axle generators to add to their trucks as per the prototype. Those, and the SKF bearing caps the sideframes came with stock, can be shaved or sanded thin and added to Atlas sideframes (after the Atlas end caps are shaved off) to give the proper SKF or axle generator bearings for CP C424’s, RS3’s, FA’s, etc. Some thin wire or string can be used for the axle generator cables. All the left (conductor’s) side axles are axle generators on CP units, while all the right (engineer’s) side are SKF end cap bearings. Note, some units later got a speed recorder on the #2 axle on the engineer’s side.

Also, one needs to add the brake rigging chain setup at the front left side. The truck sideframes are slippery plastic, but can be drilled for wires.

IMG_8782bes - Scratchbuilding Brake Chain.jpg
Above: Scratchbuilt brake chain and rigging, done with A-line chain. Some thin bits of 0.010″ and 0.020″ styrene cut to the appropriate pulley shape, and a nut-bolt-washer (NBW) bit from Detail Associates was used to retain the chain in the pulley. Some spare bits of styrene sprue were used as the chain guide (a small bit of wire bent into an eyebolt connects the chain to it), with metal wire mounts that run to the frame.

IMG_8860es - CP 4226 brake chain.jpg
Above: completed brake chain rigging added to the front left truck sideframe. Holes were drilled in the brake cylinder rigging on the truck sideframe, and the pulley and chain were fastened to it via bits of wire. I did this on the 4226 build, and retrofitted 4203 with it at the same time.

Paint & Decals

After priming the body with grey paint, it was then given a few coats of TLT CP Action Red (since discontinued, but Tru-Colour Paint’s TCP-024 is  a very good match), and then a coat of TLT Gloss Glaze clear. The underframe, cast in black plastic, was given a few coats of TLT Warm Black followed by a coat of clear as well.

Above: After modifications were complete, the body of the unit was given a coat of primer grey. At this point, the underframe had already been painted black, clear, and decalling had begun (this one is the 4226 build).

Above: after the grey was dry, a few coats of action red were applied, clearcoated, and the unit was ready for its rear multimark and lettering/numbering (this one is the 4203 build).

The multimark was then masked and sprayed on according to my handy-dandy how-to writeup. The C424’s are probably the worst units to try applying multimark decals to (and I know – I’ve wasted a lot of Microsol trying to work the decals into and around the deep rear grills on other units) so for this application it’s a real time saver and looks great. Just take a gander at 4203’s rump end:

27064bes - CP 4226 multimarks paint shop.jpgAbove: spraying on the initial white after masking the round section. Unlike using decals, there’s no hassle getting it into the deep grill area at the back!

Above: no decals, no Microsol, no poking, no prodding, no fuss, no muss. A painted on C424 multimark is its own reward.

TLT warm black was used for the underframe and fuel tank, as well as the black parts of the multimark and rear end area, and TLT stencil white for the white areas of the multimark. The handrails were painted similarly (be sure to paint the bits of the handrail stanchions below the underframe black, a lot of people miss this detail). The step faces were carefully painted white, along with the fuel filler (varied, could be white or red). The bell was given a mix of gold-silver to make it appear as a shiny brass bell like some units had.

The decals were from the usual Microscale CP lettering and 5″ stripe sets. The front stripes took a few tries to get lined up correctly, as due to tooling and printing differences they don’t always exactly line up like the prototype. Working them around some of the numberboard/class light/window details on the front cab face was a challenge, and some had to be applied in bits and pieces, and touched up with paint. All the cab window, numberboard and class light gaskets were then hand painted black. The rear number was originally black numbering on a white background, but eventually changed to white numbers on a black background. No frame dots for the mid-70’s era units.

Above: CP 4203 on the “shop track” getting decalled. Handrails still need to be repainted, as does the fuel tank, and a lot of other bits need to be added.

Above: cab and end decalling progresses. The numberboards were later filled in with styrene bits, painted black, and decalled.

Additionally, some class decals came from a Black Cat CP maroon & grey unit set (sometimes units retained their yellow-outlined class plates, instead of having them repainted). The front numberboard cab decals in the Microscale set are a bit too large for CP’s C424’s, so the slightly smaller ones with the Black Cat set were used (and look great). The builder’s plate on the right side under the cab is a modified Microscale one to act as a stand-in for an MLW builder’s plate (I’m not aware anyone makes a correct one).

The fine plastic wipers were painted silver and glued in the holes drilled earlier in the cab. They came from an Atlas GP38/40 wiper set, and were close to what the C424’s had.

Glamour Shots:

Above: CP 4203 front-left view. Note all axle generator cables installed.

Above: CP 4203 rear left shot. Note the open rear pilot area.

Above: CP 4203 rear right shot. The sun was setting and low at the time, hence the unintended shadow of the photographer.

25656s-CP 4203 C424 & 8492 GP9.jpg
Above: CP GP9 8492, a custom chop-nose GP9, also came out to play in the sun.

Above: CP 4203, right side view.

Above: messy shop desk parade: CP 4203, 8492, 8163 & 8485.

Addendum: CP 4226

A few months after completion of 4203, a second unit was started using the same methods (and some improvements noted above), done up as sister unit 4226.

Above: CP 4226 front left view, note the brake chain rigging and more accurate drop steps were added to this build.

Above: CP 4226 rear right view. Pre-roadswitcher end pilot cutout featured on the rear, as well as blank rear end with single top headlight. Note rear number, earlier repaints had black numbers on a white rectangular background, but that changed later on to white numbers on a black background.

Above: CP 4226 front right view. Also note, the red (steel) bell on this unit, as opposed to the brass one on 4203.

Above: CP 4226 rear left. After rebuilding as roadswitchers in the 1980’s, that as-delivered front horn would be relocated to near the rear exhaust hatch area (position could vary).

Above: CP 4226 and 4203 side-by-side. One can notice a very slight difference in shade between both units (even though the same TLT CP Action Red paint was used on both), caused by using a gloss finish on 4203 (TLT Gloss Glaze clear) and a semi-gloss finish on 4226 (Model Master Semi-Gloss clear). This is only really noticeable in bright light conditions such as this, and paint did vary on the prototype depending on how fresh or how old a unit’s paint job was.


About mrdan8530

The power of a thousand monkeys on typewriters is all for naught without the knowledge to pen.
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2 Responses to CP Rail 4203, MLW C424 Build & Paint-up

  1. Anthony T Gentile says:

    Mr Dan.your work is awesome.I think I’ve seen you on Diesel Detailer.These 424s are ridiculously good-I can see myself trying to bend the classlight housings and impaling that thin wire in my flesh….
    Wish an updated superdertailed version of these mlw-/alcos was available,similar to what rapido is doing with some of their models.
    Talk to you,
    Anthony (mta224 on diesel detailer).


    • mrdan8530 says:

      Hi Anthony, thanks for the comments! I used to do some posting on the DD, but over time moved most of my stuff to the Canadian Railway Modelers Facebook group (and use this blog for long-style project write-ups). It would be nice to see an updated C424 on the market – as nice as the Atlas units are (and they are smooth runners), they leave a bit to be desired in terms of different road-specific details. Rapido’s going to be busy with all those RS11/RS18 versions, but I could possibly see them thinking about it off in the future (the C424’s sold much better in Canada than in the US IIRC). Bowser is a possibility as well. Atlas doesn’t seem to be as active as they once were, so them revamping their current units may be a long shot.


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