I HAVE AN ON CENTER BLOCK MADE 3/96 IT HAS CROSS BOLT FRONT AND REAR MAIN CAPS BUT NOT CENTER CAPS THEY ARE ONLY SPAYED BOLTED I HAVE SEEN PICS OF THE BLOCKS WITH CROSS BOLTED CENTER MAINS (6 BOLT MAINS) I THOUGHT MY BLOCK WAS THE LAST OF THE RUN WHEN WAS THIS BLOCK MADE WHAT ARE THE OTHER DIFFERENCES IF ANY DID THIS BLOCK COME AFTER MINE?