There are a few other railroads that had these also, Santa Fe and New York Central to name a couple. Ted Culotta has an excellent kitbashing article in:
On Saturday, March 23, 2019, 7:32:19 AM CDT, mopacfirst <ron.merrick@...> wrote:
Might be possible to combine the end door from a Proto boxcar with a Proto 50' single door body.
As a general practice, 50' single door cars with end doors were very rare, and the 1942 build date suggests something specifically built for a defense plant contract. The hoist suggests something heavy like aircraft engines.
This car is probably well documented by Burlington specialists, so I hope one enlightens us.