Hello Tom. The replacement engines had their own prefix number, without a suffix like the original stamped blocks. The block is an early 512 casting, dated the second week of March 1969. I believe the 8 is a 9. The 512 blocks were not cast in 1968, and were late 1969.The stamped number on the pad is a CE, for warranty block, not an Engine casting #. The 963353 is a control number for warranty inventory. I would stamp the suffix when I replaced an engine under warranty, but not stamp the Vin number like production. That way You would know what block was used. What car is this engine in? NICK L72 Chevrolet Technician 1960 to 1980's.