These "Golden Brass Series" kit cars were released by NGI (Chicago) in the mid-70's. They consist of a lucite plastic floor, a couple of white metal castings (tanks, metal bolsters, etc), a Con-Cor Budd-style roof, and photoetched brass ends and sides. They were available either prepainted or undecorated (with decals for various roads included with the latter). Trucks and couplers not included.
I'm not sure what prototype these might be based on, but my assumption is Pullman/C&NW.