Modeling IAIS 700-721 in HO

By Joe Atkinson
More information on the prototype IAIS 700-721

Until Atlas introduced their factory-painted IAIS GP38s, IAIS GP38-2s 700-721 were, in my opinion, among the easiest of all IAIS units to model, though they still require a number of changes and additions to accurately represent the prototypes. This article is based on my choice to start with the Life-Like Proto2000 GP38-2 for my models, though the Athearn model with the smaller fuel tank could also work with a little more effort. If you go with the P2K model, you'll want the variant with the 81" nose, standard dynamic brake blister, 2600 gallon fuel tank (the smaller of the two available), and Blomberg-B sideframes. The undecorated model offers these options, as does the Conrail unit. The NS-painted model has everything but the correct sideframes, and it offers the added bonus of handrails that are molded in the correct colors for IAIS units. If you go with the NS model, Blomberg-B sideframes can be ordered from Life-Like.

While the IAIS 700s all appear to be identical at first glance, there are quite a few interesting detail differences that set them apart from one another. Among them are variations in the following, examples of which may be found by studying the prototype photos elsewhere on this site:

  • Cab numberboard grab iron placement - Most units have the cab number board grab irons above and below the conductor’s side number board, but 706, 714, 715, and 721 have them on the engineer‘s side.

  • EOT antenna placement on the cab - Opposite side from the grab irons described above. Note that sometime during her first six months of service, 718 had her can-style EOT antenna replaced with a firecracker-type.

  • Horn type - All mounted in front of #1 radiator fan, centered on long hood. Horn types used are as follows:
    * Leslie S3L (P2K factory horn) - IAIS 701, 707, 708, 713, 717
    * Leslie S5T (Similar to Details West #191 or Overland #9017) - IAIS 709 (Had S3L until February or March 2005)
    * Nathan K3 (Overland K3, or modified Overland K5) - IAIS 702, 704, 705, 706, 710, 711, 714, 716, 718, 721
    * Nathan P3 (Details West #175) - IAIS 700, 703, 712, 719, 720
    * Prime PM920 - IAIS 715

  • Exhaust stacks
    *Low-profile on at least 707 and 708 - Trimmed and sanded factory stacks
    *Extended stack inserts on 711 - Modeled with short sections of 3/32“ aluminum tubing crimped into oval shape and inserted into factory stacks.
    *Two extra stacks on 719, mounted inboard of the factory stacks. These were apparently added by Conrail, but were capped sometime later. I modeled them using Detail Associates #2402 stacks, simulating the caps by filling them with Squadron green putty and sanding smooth.

  • Lift rings - 719 has four extra lift rings on dynamic brake blister.

  • Toilet vent location - The most common position is horizontally mounted on top of the short hood in front of the conductor‘s side windshield pane, though 710 has it located on the right side of the short hood, mounted vertically.

  • Cab vent - 718 has an oval vent on the engineer's side of the cab. I used Detail Associates #1902.

  • Plow style - Wide variety. Many can be represented by modifying the plow Life-Like includes with the GP38-2, but for others, such as those on 708, 709, and 711, I used extra plows from Atlas GP38s. On some units, I haven’t yet found a good match in HO scale.

  • Coupler cut levers - 702 and 718 have been retrofitted with a more modern style, but all other units have extensions welded on the factory cut bars. To model these, 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. Drill holes in the pilot immediately behind the point where the cut bars turn downward 90-degrees, and glue the bottom portion of the extensions horizontally into the pilot.

  • Fans - Most IAIS 700s have low-profile fans that are the same height as dynamic brake fans, but 707 has two standard-height button-top radiator fans, and 706 has low-profile in the #1 position and a standard-height open-top fan in the #2 spot. I replaced all P2K fans with those from Cannon & Co., using their #1702s for 707s radiator fans, #1704s for all other standard-height radiator fans, and #1853s for all dynamic brake and low-profile radiator fans

  • Rear pilot MU hose pockets - At least 706 and 708 have these. I fashioned them from wire grab irons and thin cardstock.

    Other additions and changes that that are common to all 700s are as follows:

  • Air hoses - Details West #267 or #302, as appropriate

  • MU hoses - P2K factory parts, bent to more natural positions.

  • Class lights - Removed and sanded smooth.

  • Grab irons - In order to apply decals, most factory grabs were replaced with Detail Associates #2202 grab irons. I cut the factory grabs free from the attached nut/bolt castings, instead of pulling them out, so I could reuse the latter with the new grabs. Factory grabs on the top and front of the short hood were left in place.

  • Trimmed notches in upper corners of pilots.

  • Added plate made of 0.010" styrene to bottom of rear pilot.

  • Fashioned EOT antenna from shortened P2K factory firecracker antenna, with stem used as a mounting peg, inserted in hole drilled in cab roof.

  • Added Hi-Tech Details #6009 waste fluid retention tank to rear of fuel tank (not yet shown on models of IAIS 707, 708, 711, or 718). On more recent 700s I've completed, I've also been adding the Cannon #2156 fuel tank detail set, as well as using leftover bits of piping from the set to detail the waste fluid retention tank.

  • Added Details West #139 air filters.

  • Added Details West #196 spare coupler knuckles with brackets (2) to the rear pilot.

  • Added Details West #274 Sinclair radio antenna to cab roof. Placement is illustrated in the Andy Brown photo of IAIS 711.

  • Ditch lights - Details West #229 front and rear (not yet shown on models of IAIS 707, 708, 711, or 718)

    Painting was accomplished largely as described before, but on the 700s, I used a different yellow to simulate the deeper shade brought on by the clearcoat application these units received. On the first four 700s I completed for a friend, 707, 708, 711, and 718, I used Scalecoat 2s Reefer Yellow. However, I continued to experiment, and on subsequent units, starting with IAIS 719 shown here, Ive used Scalecoat 2s CNW Yellow.

    The nose herald and SmartStart logo and warning stickers were custom decals, but ORO Decals has since released an IAIS set that includes these.