Here's a collection of C&O's ex-Pullman troop sleepers in MW service. Not exactly freight cars, but IIRC we agreed MW cars counted. The Allied Full Cushion truck appears to be from a different car than any pictured here.
IIRC, some of these cars were used by the C&O for express or mail storage. 910239 is probably one of these, and hey!, it's a boxcar (of sorts). Note that the numbers on this car, 911150 and 911153 are in white. So much for system standards.