Slant 6 engine stamping help.

The block number is more like that of an mid-early block. Does it have 3 core plugs in the driver's side of the block or 5? Of course if it has been rebuilt, then all bets are off to decipher the crank pilot sizing by the block numbers.

One problem that has confused me is that service part numbers (i.e., replacement part numbers covering several years and parts variations) have been publised as production numbers. So many PN's you find published are not accurate as to production PN's.