I'd say there's a good chance it had a later 302 swapped in but you would probably have to check numbers to be sure. All of the 1.5 tons (single drive axle) I've seen have been the Chevrolet versions so I would guess it's not original to the truck. My '42 Chevrolet military truck just has a 216 but it works fine to plow snow and move stuff around the farm.

Joe McNeel

http://mcneelnet.com/~jmcneel/59.html