Well you got me there. I thoughts these cars were refrigerated, and always thought milk cars ran in express trains. I always associate milk cars with them funny lookin' butter dish cahs.
My point was... there's a correct wood car in the old Roundhouse car (now Athearn), a correct steel car in the IMRC car, and the IMRC 6-panel would be the closest, IMO, to the more standard looking box car car.