I have a 1957 Chevy Belair 2 door with window posts. The engine seems like it is not stock and looks like a 350 Engine to me. When ordering parts I specify a 350 engine and seem to get parts that work that is I have ordered a starter, and freeze plug. I have a tag on the engine that says:

STOCK NO.
H007068
Rebuilt Engine
Power-Pak

I recently lost the harmonic balancer (It fell apart) and I am trying to figure out what year the engine is as most of the parts stores want to know that information. I know that the engine most likely has a serial number or casting number on the rear of the engine near the bell housing (how convenient), but I doubt that I can see it without pulling the engine. The engine runs great and has lots of power, it doesn’t smoke and the previous owner put on all sorts of chrome so it looks great. Any thoughts on how I can identify this engine’s year would be very helpful. Including figuring out how to get to the casting number without pulling the engine.