>>>> I picked up an old IMRC GN 12 panel boxcar kit (GN 18837, reweigh F-10-60). Some of the parts are pretty dated. There were no instructions and I have a few questions.
Out of the box, the IMRC 10’ 0” 12 panel cars are accurate for zero to one version of the GN 12 panel car covering 3 number series:
Whether they are accurate or not depends on which version of the end IMRC included in the kit you purchased – some have a 4/3/0 end, some with a 4/3/1. For the three GN series above, _only_ the 4/3/0 version of the end is accurate. Ed Hawkins defines this as:
42798 IDN-1 - 42798 Improved Dreadnaught End with rolling pin main corrugations and lacking top narrow stiffener (1945-1948)
The doors included with the kit may or may not be correct for the series in question, either. Again it is important to look to Ed Hawkins work on 10’ cars for these and other details.
No other series of GN 12 panel cars can be modeled with any ends provided by IMRC. The remaining GN 12 panel cars use what Ed Hawkins calls IDN-2: 42798 IDN-2 - 42798 Improved Dreadnaught End with rolling pin main corrugations except top main corrugation with truncated bottom (mid-1948 to 1953). To my knowledge, no one provides this end to the HO market. I’m currently working on creating some masters for my own use based on techniques Bill Welch discussed in one of his clinics in the past couple of years. If such a 10’ end exists I’d love to hear of it. One also needs to pay attention to the correct doors for the various series, too. Again, I refer you to Ed Hawkins work on this group of cars.