[51504bat]

Hard to tell from the photos but it appears that the engine has wide belts. If so its a 1949 Merc unless the pumps and related pulleys were changed from narrow belts to wide belts. If the belts are narrow it has the OCM Merc pumps from '50-'51 if I'm not mistaken. In '52 or thereabouts Merc went to Ford narrow belt car pumps. Or if the pumps are wide belt it could have 8rt truck pumps. Lots of stuff got changed around in the last 70 or so years. A photo showing the front of the engine would help narrow the pump issue down but the only way to know for sure if its a true Merc is to measure the stroke. I once bought what was said to be a Merc engine without pulling a head. It had Merc narrow belt pumps, a Merc pan, and a Merc stamped steel 1/2 bell housing. When I tore it apart it has a 3 3/4 crank.