Mike,
See Colin's
CMP webpage for a picture showing all types of bodies for CMP 15-cwt trucks, copied from Bill Gregg's "Canadian Military Vehicle Profile Series" Volume 2.
Steve Guthrie posted the dimensions of the 2C1 body in the thread
C15 Box Weight. Steve got them from the AEDB Vehicle Development Record; this publication might have drawings as well.
I have neither publication, but I know some forum members have them so they might be able to help.
Good luck!