Over on the Kalmbach forum, there's discussion about the identity of a car in a photograph:
I get the car having 4 6-wheel Buckeye trucks. Capacity is 500,000 pounds. And build date is February 1941.
Does anyone know what the reporting marks might be? I can't find anything anywhere near the numbers above.
The big thingy is JUMBO. It was designed to contain a non-critical detonation of a plutonium bomb. And it weighed a lot.
Here is perhaps a better copy of the photo: