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  • Western Pacific's Bi-centennial EMD GP-40 in HO


    Photos are by the author.
    Prototype Modeler - December 1978 - Page 56 Prototype Modeler - December 1978 - Page 57

    The EMD GP-40: a very popular model purchased by almost all major railroads. The Western Pacific has purchased forty of these locomotives in three different orders, number series 3501 to 3544. The No. 3516 was the last of the silver and orange GP-40s.

    These locomotives are today painted green, the shade is referred to as Perlman Green by the WP. Early in 1977 Western Pacific painted two units, the 3540 and 354 1, with bi-centennial colors. The units appear to be a cross between the Seaboard Coast Line and Burlington Northern's bi-centennial garb.

    Since my regard for Atlas locomotives is not the highest, I decided to build my HO GP-40 locomotive out of Athearn shells and parts. Using this conversion I am assured that my model will not only pull significantly better but it will outlast the Atlas model probably five to one. I found splicing the under frames very easy and it looked nice when finished.

    I suggest that if you decide to tackle this project you throughly study the photos and diagrams provided. The drawings are keyed to the article such that the number shown on the figure matches the number in the article. This project will certainly build your confidence as a modeler and will result in a very reliable unit. You will be pleased with your effort.


    Remove all casting flash from the GP-35 shell. Remove the cast-on nose headlight and replace it with the head light from Detail Associates. Fill behind the headlight plate with putty and, when throughly dry, sand smooth using at least a 400 grit sandpaper. Remove all cast-on grab irons; I used an X-Acto No. 11 blade and it worked well. Leave enough of the grab iron so that you can use it to locate the point for drilling new grab iron holes. The holes should be drilled in each cast on bolt location (see Figure 3). Do not install the grab irons even after the holes are drilled; they'll be added later.

    All Drawings by Dan Crews. Photos are by the author.
    Prototype Modeler - December 1978 - Page 58 Prototype Modeler - December 1978 - Page 59 Prototype Modeler - December 1978 - Page 60

    While the GP-35 body shell is still basically intact, work on the extending and reducing of the dynamic brake (see Figure 2). Filling and sanding is essential here to retain a good appearance.

    Though body splicing is considered difficult by some modelers it is really quite simple if the necessary time and care is exercised when the actual cutting is done. Mark the shell with an X-Acto knife before cutting any portion. This will help to align the cut when it is started.

    Following Figure 1, cut the GP-35 shell just outside the marks and with a file make the cut match the line initially drawn with the X-Acto knife. Do the same with the SDP-40 shell. It is important that these cuts be straight so that there will be a straight shell as the end result. When you are sure that they are satisfactory place a rubber band around the matched portions and cement them with Micro Weld or some similar solvent cement. Allow to dry thoroughly before removing the rubber band.

    User a wet-or-dry type sandpaper of at least 400 grit (600 grit is even better) and sand the joints. Be careful to avoid damaging any adjacent doors, handles, hinges, or other related details.

    The Dust Exhaust Cover most be removed from the SDP-40 shell and reinstalled on the new GP-40 shell you're making (see Figure 5). The clips used to mount the Athearn shell to the underframe should be removed. A small hole will be left that must be filled with putty.

    Give the shell a final sanding with the finest sandpaper to remove all signs of modeling activity such as scrape marks, joints, etc. that would mar the completed model. Paint the shell with a prime coat; this is an excellent method of showing up any marks that just can't be seen without the benefit of painting. The bi-centennial paint job is quite difficult since there are so many different locations that must be touched up with a mixture of paint.

    The number system will try to solve this problem.

    I first painted the blue stripe on the nose, body stripe, and the top of the roof. Follow the figures for proper paint ed areas. The cab roof, body stripe, and handrails are red. Mask the red and paint over with white, Touch up the bleed-over areas and allow the paint to dry.

    Using Herald King decals, apply them to the shell using the instructions with the set and what is in this article. After the decals are dry, apply the stanchions (follow the photos for correct shape).


    The MU (multiple unit) receptacles are just off the drop steps (see Figure 3). Make sure when applying all Detail Associates components that you use very little cement; the parts are very fragile (this is what makes them so excellent).

    The grab irons should be removed from the shell. Leave enough, however, to know where to drill the holes for the replacement grabs. Mark each hole just below the cast on bolt with a pin. Use a No. 79 bit and drill the holes for the re placement grab irons. Apply the grab irons through these holes; trimming 3/16" off the ends make them easier to install. The list below will correspond with the drawings on where to install the detail parts and what color each should be.

    1. Nose Headlight: Detail Associates No. 229-1007. Before installation it is necessary to remove 4" from the nose (see Figure 2). Number 9 on the drawings is the headlight; number 10 is the Backing Plate. The Plate should be 1'-3" x 2"; use the thinnest styrene available. After cutting the nose section, taper the bottom and mount the light and plate as shown in Figure 2. Paint the light only red.

    2. Horn: Detail Associates No. 229 The Nathan five-chime air 1602. horn should be mounted above the upper headlight. Paint it red.

    3. Antenna: Made from telephone wire. The main stem is 12" long and the insulation is cut to 7". Leave just enough room between the roof and the insulation to allow the wire to show.

    4. Awning: Detail Associates No. 229-1301. The sun-shade should be mounted as directed by their instructions. Paint the awnings red.

    5. Electrical Cabinet: Details West. Mounted just behind the brakeman side of the cab. Paint it white.

    6. Dust Exhaust Cover: Remove this from the SDP-40 shell; file it down to the proper height and cement it to the SD-40 shell; paint it blue.

    7. Dynamic Brake Vent: Details West. Mount the vent by using the draw ing with this article (see Figure 1).

    8. Roof Strap: Make this from the thin nest styrene available. Cut it 3" wide and allow it to drape 2' on each side of the shell.

    9. Nose Headlight.

    10. Headlight Plate.

    11. Nose headlight cutout.

    12. Blue Stripe for nose.

    13. Athearn underframe clip. Must be removed and the side filed flush with the body. Fill in the small hole that is left.

    14. Grab iron: Detail Associates No. 2292202. Paint these blue on the front of the nose. Those on the top and side of the nose are red. The rear grab irons are all white.

    15. Drop Step: MU receptacle 229-1401229-1505. Follow the instructions that come with the components. Also, follow Figure 3. Note: The stantions are white. All handrails are red. The two grab irons on the plow are red and the plow is blue. The coupler pin lifter is red.


    You will need two GP-35 under frames, one powered and one dummy. These should be cut to size by following Figure 6. After the cuts have been made, use a fine metal file and trim the cuts so that they are square. Place the two parts of the frame together and hold them with a strong rubber band. Cut the two brackets to size so they will fit inside the body. Drill the holes, tap them, and install the braces. If they seem to fit nice and snug, add some cyanoacrylate cement between the cracks. Let it dry throughly; file the tanks area and sand it smooth. Note: Be sure the frame is in-line and flat.

    It will be necessary to fill the cracks in both the tanks. I used wood, cut it to the proper shape; put putty over that, allowed it to dry, and sanded smooth again. Using the drawings, put all the details on the tank. One gauge is inset in the tank; this was done with a Dremel Tool.

    The biggest part of the project was to Dremel 1/8" off the frame all the way a round. This is very important. On the other side of the GP-40 the height notches have to be removed. After this has been done, the shell will fit nicely and flat on the underframe. Air tanks were made from 1/4" plastic dowel and installed.

    The whole underframe, including the trucks, was painted blue. Apply the chain drive and trucks. Couplers fit nicely and are still in proper gauge. The front nuckle magnetic arm was cut off for a better look.

    Article Details

    • Original Author Dan Crews
    • Source Prototype Modeler
    • Publication Date December 1978

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