I've always been interested in these cars, ever since the late Stan Rydarowicz wrote an article on them in Railmodel Journal. I have also seen an unsigned article in the February, 1987, issue of Model Railroading. Combining these two sources with Ed Hawkins' roster of 1937 AAR boxcars yields the following information. I would welcome corrections.
B & O 465000 - 465899, lap seam roof. Photo in MRG article.
C & EI 1 - 5, express boxcars
CGW 91000 - 91099 and 92000 - 92149, the subjects of these mini-kits. I seem to remember reading somewhere ( Dr. John Nehrich?) that one group of CGW cars lacked stiffeners in the roof panels, but I can't find the reference.
TC 7900 - 7999, lap seam roof. Mr. Hawkins does not list these cars as having the P/S end, but photos show that they did.
WLE 24200 - 24501. Photos in Mr. Rydarowicz' article do not appear to show seam caps, so I think these cars also had lap seam roofs. The WLE purchased 200 cars from AC & F at the same time which, oddly, did have Pullman roofs.
I certainly don't claim this list is exhaustive, nor do I claim to have done any original research.
As Mr. Rydarowicz points out, there were taller cars with 5/5 ends.
I hope my modeling efforts will someday look as fine as thise shown in this thread.
With the availability of these ends, a lap seam roof would sure come in handy.
Thank you for the opportunity to make these comments.