Those non-GM car haulers came from my Flickr pages. Whitehead and Kales built about 10 of the Dodges for Comm Carriers about 1950. The Convoy was also one of about ten Convoy built in their shops in Portland. Other photos and details on Flickr. Bay Colony mentioned overhang. Look at the over hang on this rig.
GMC Cracker box; Insured #154 by
Dick Copello, on Flickr