Just got this one off daBay. Old Athearn, maybe All-Nation, 50ft kit. Previous owner had put some nice Lionel die-cast trucks on it (too far outboard - 3-minute re-drill and move mod) and it has a good paint job and lettering.
I've said it before, I like these old metal kits because they look...metal, like the real thing. Thin cross-section material. Not as hyper-detailed as the new stuff (which is beautiful), but I don't care.
Often inexpensive, too - especially if already in the 3RO configuration, as this one was. And, if assembled correctly, pretty robust.
Essentially all the underbody detail that I typically need.
Unless you've had a wreck...