Just found this 21 marking in grease pencil on the front of the block just below the driver side head. In the 62 inspection book I found engine code 21 is for the manual transmission low compression engine so I assume this is not the engine code. I am guessing it is just some random inspection number that is not in the book. According to it, this engine should be code 30 and on tape. I have not found that any place and no clue where it would have been when they put the tape on.