Wow, what a beauty! Check out the fishbelly underframe, unusual arch bar trucks, and Youngstown replacement door.

36' box, RDG class XMp, built 1912-1913.
ORER series is 11550-13549, 987 cars 1/43, 33 cars 1/53.
Builder's photo: Kaminski, "AC&F", p 163 (the end straps were original equipment, as were those trucks); order said to be 1000 cars, so the ORER may have combined orders into one series.
Two photos of a covered-hopper conversion (you 'eard!): Bossler, "RDG Color Guide", p 63.
End-on in-service shot: Pietrak, "Coudersport & Port Allegancy and New York & Pennsylvania", p 67.

If I were building that, I might kitbash it from a Roundhouse old-timer box body, and a shortened Accurail reefer underframe. Not sure what to do about the trucks, might cheat and give it more modern ones. (The covered hoppers mentioned above have AAR cast trucks.)

Al Brown, Melbourne, Fla.