I am trying to determine if the 350 short block in may 1968 Firebird is the original, previous owner says it is, but not sure how to confirm. I have found one set of number and letters stamped on the block, which does indicate the correct year/type engine for this car (I do have the PHS files). However, I have been led to believe that there is a partial VIN stamped somewhere on the engine, but I cannot find it. Any advice here?