the only clue I see that I can identify (as a non-expert) is that the bolster on the trailing truck looks like bolsters I had on some Lobough trucks. It also looks installed upside down. This might mean someone did some custom work to get it to fit.
Lobough did make a kit for a UP challenger that was still available into the late 50s or 60s. That might imply that some or all of the mech was from a Lobough kit.
