Then it's not an original engine, if that helps or hurts. 
Looking down on the engine from above, passenger side just behind the alternator (typical) there is a flat "pad" on the block (not head) that you would be able to read.
Wouldn't be uncommon for the *stampings* (small and sometimes kind of light) to be obscured by years of crud.

Looking down on the engine from above, passenger side just behind the alternator (typical) there is a flat "pad" on the block (not head) that you would be able to read.
Wouldn't be uncommon for the *stampings* (small and sometimes kind of light) to be obscured by years of crud.
