The pad that has the identifier is on the passenger side just in front of the head....it is part of the block deck that is broached flat for the head gasket surface. There is usually two lines of stamped numbers (not cast). There is a two or three letter sequence. From this, you can decipher several things about the original installation (but not always): the year, the body style, the carburetor, automatic or stick shift, and the horsepower.

The casting number on the back of the block on the top of the bellhousing identifies the part number of the casting only....it doesnt even tell if the engine is a two bolt main or four bolt main.

The Mortec site is an incomplete list but is better than nothing. A better list is available from MSA-1. IF you post the identfier, I have th MSA book that ranges from 1955 thru 1999 for codes and casting numbers

mike in tucson