If it is a 1951 Canadian 216, it would have a short side cover (like a 1951 235).

Later 235s/261s also have the plug in the center of the passenger side of the head.

Dave, why is it clear that it is a 235?

Did 1430 (1 ton) 1951 Canadian trucks come with a 235?

1951 USA 3800 trucks came standard with a 216 and the 235 was not an option.

Carl, why does it look like a Powerglide?

Of course, it could be a replacement engine. Castings codes (including date casting codes) and the engine serial number would clear up the speculation.