Thanks Dave and Kev, more info - this engine was removed from a light pickup - 5 yr ago - so has been sitting for a while - the water pump is seized pretty solid. It was on it's way to the dump when it was "rescued". It is supposedly a 1951 GM 235. The engine serial number stamped on the flat area behind the distributor is 463608 - which doesn't match any of the patterns I see for US engines, so I'm guessing it is a Canadian version. (my 1950 GMC 216 is C377402 in the same location) The dimensions of the rocker cover and location of the engine mounts look pretty much the same as my 216 (two bolt rocker cover) The generator is the same serial as mine (6 volt), and the distributor is "Delco Remy Made In Canada 1112364 - which my book says was in the 1951 1/2 to 1 1/2 ton truck BUT - the trans. is shorter - mine is 13 3/4 " as you noted, but this one is only 12 1/2" Photo attached I have the 1948-51 Maintenance Manual for Chevrolet GMC Trucks (General Motors Products of Canada Limited, Oshawa, Ontario) It only lists one version of the 3 speed transmission for those years - looks like mine, but this one looks different.
Any idea what this trans is, and if I could make it fit?