By Joe Atkinson
More information on the prototype IAIS 625
More information on the prototype IAIS 626
More information on the prototype IAIS 627
More information on the prototype IAIS 628

IAIS 625-628 are ex-GM&O GP38ACs (originally GM&O 721, 725, 729, and 731 respectively). Built in the Spring of 1971, they are Phase 2c GP38s (GP38ACs). The comments below are based specifically on my experience modeling IAIS 627 using the later phase HO scale Atlas GP38, but I've tried to point out any differences with the other units in the series.

GP38ACs have the "beaded" blower bulge on the left side. The blower bulge may be replaced with Cannon's "late 40 Series" item, or you can add the beads to the Atlas blower bulge using thin strips of styrene. I chose the latter on 627, but used the Cannon part on 625, 626, and 628.

Handrail stanchions on the GP38AC long hood are spaced about 48" apart, causing the first stanchion to be closer to the cab. Earlier GP38 phases, such as the Phase 2b2 that the Atlas model is based on, have the rear-most stanchions closer together. I elected to ignore the handrail spacing issue, as I wanted to use Atlas' nice one-piece handrails.

IAIS 625 and 626 had access doors added on the engine room roof during their time on the ICG, but 627 and 628 did not. I'm using strip styrene to model them, but you could also use Cannon doors.

All four units have extra jacking pads near the stepwells as ordered by the GM&O. On 627 I cut these from a spare walkway and cemented them in place just inboard of the stepwells on each end. On 625, 626, and 628 I'm using Cannon #2153 jacking pads. They aren't correct for GP38s, but they're a decent stand-in until Cannon offers the correct part.

These units have 3000 gallon fuel tanks, which are 14' 9-1/2" in length. I'm not sure if Atlas intended to do this, but their placement of the front partition on the 3600 gallon tank (the larger of the two included in the kit) is perfect for the front of the 3000 gallon tank. Cutting it off ahead of this partition leaves the fuel sight glass exactly 19" from the new front, exactly the distance on the IAIS GP38ACs.

Given that, in order to shorten the tank further to its prototypical length, it's necessary to do so from the rear so as to retain the relative location of the fuel guage hardware. The removal of the front of the tank leaves it 15' 6", so removing another 8-1/2" from the rear will bring you to the correct prototype length. I did so by first removing the rear plate of the tank and the rear partition, then making a second cut from the tank itself to remove the remaining length, being sure to account for the thickness of the rear plate in determining how much of the tank to cut away. Sand the rear plate and the back of the tank smooth and bond. If filling and sanding are necessary, do so carefully so as to avoid rounding the right angle at the rear of the tank.

The Atlas tank comes with a skirt that extends vertically from the tank itself. The rear portion of this skirt is hidden by the air tanks, but the front, forward of the first notch, is visible and hides the prototypical view of the frame. Atlas also incorrectly molded the hole for the fuel tank fill pipe into this skirt - it should be in the top of the tank. Trim off the skirt forward of the first notch using a sharp X-acto blade to scribe a few times at the joint between the tank and the skirt, also scribing up and over the fuel site glass and around the joint between the skirt and front tank bulkhead. Snap the skirt off and file the tank smooth. Drill a new hole for the fill pipe at a 45-degree angle, 7" from the front of the tank and about 1/3 of the way down from the top. Add the fill pipe. Remove the molded-on drain hose from the old front fuel tank bulkhead and add it to the new front. Add the air tanks and associated lines as per the instructions.

On 627's cab, install a Nathan P-3 horn (Details West AH-175) in the hole Atlas provided. Add a Sinclair radio antenna (Detail Associates #1803) slightly more than half way back, centered on the cab roof. Midway between the two, 627 carries a strobe flasher. Since I've never seen a modern strobe flasher offered commercially, I represent these with Details West RB-126 with the top of the amber lense filed flat. Don't add the flasher to the unit until painting is complete. Install the Atlas wipers, adding a thin wire or styrene brace extending horizontally between the two center windshield wiper arms in front, about 4" down from the top.

Notch all four upper pilot corners (except on IAIS 625) and add the Atlas coupler cut bars. Fashion 22" wire extensions for each corner so that the upper 12" extends above the cut bar, angling slightly away from the end of the unit. Note that the extensions added to 627 have no loop of any kind. Drill holes in the pilot behind the point where the cut bars turn 90-degrees, and glue the bottom portion of the extensions horizontally into the pilot.

Remove the footboards from the MU hose pockets provided in the kit. Separate the hose pockets from the center bulkhead that joins them, then make a horizontal cut through each hose pocket. File the resulting D-shapes down, rounding the outer corners, to represent the MU hose brackets that IAIS adds to many of its units including 627 (though not yet added in the above 1995 photo). Fill the five unused holes that Atlas provided for the MU pocket/footboard assembly by applying CA from the inside. Attach the MU brackets to all four corners of the pilots centered under the holes for the MU hoses and at the same height as the holes just filled. (Note that I'm not doing these pockets on 625, 626, and 628, nor any future IAIS units, until I find a manufacturer to do a run of them as a custom photo-etching project. Until that happens, I consider it too much work to do four of these in plastic for every unit I build.)

In the kit there are two sets of straight MU hoses and two sets that have a slight jog in them. I added the latter to the rear of 627, giving the appearance that they're dangling outside of the MU brackets. The straight hoses were tucked into the front brackets as is often the practice on the IAIS. Since modeling 627, I've switched to using Details West #294 MU hoses for all my models, since they have a nicer appearance and can be positioned to hang more naturally. I also use only DW #267 or #302 air hoses now, for the same reasons. IAIS 625, 626, and 628 feature the DW hoses.