I have bought and are currently restoring a 1968 Howe fire engine. it appears to be a Chevrolet cab with a GMC power train. the owner manuals that came with the truck have the 478M circled in it identifying it as the engine that is in it. But I have been unable to locate the engine code on the block. the engine runs great and only has 24k miles registered on the odometer. I m new to the site and if I can figure out how to post pictures I will.