One car I had wondered about and had seen reference to is the tank car made by Hawk. I have yet to see one but a correspondent supplied this instruction sheet.

I think personally the most interesting thing about this instruction sheet, besides this being evidence that this car exists (!) is the date it was introduced. Their 40’ boxcar instructions for example (which show a photo of most the other cars in the line [the 50’ steel boxcar, the 40’ outside braced boxcar, the gondola, and the steel caboose]) is dated Dec. 19, 1940. This instruction sheet however is dated April 20, 1942. This all wood kit was in production and indeed introduced in the middle of WWII.

If anyone has a photo of a built up car I would be happy to add it to this post. This is certainly a car that is quite uncommon.