I was looking through old MRs, from the years when they were packed with articles, and came across a mention of prewar wooden boxcars that were needed for war traffic. they had their roofs raised and sides added to so as to get a 10'6" interior height. There was also a small picture of a model of one, but hard to see details. The article said some of these lasted through the '40s.
As an interesting model I'd like to modify some MTL 40' single sheaths into these conversions. Any place where I can get some helpful pictures of either the prototypes or models, hopefully large enough for me to see the detail of the extensions? The extension also made it possible to replace the original wood doors with taller steel ones, like steel boxcars had.