They rough bored it 3.79 if I remember right. The info about them has gone the way of the DoDo bird but you can find tons on production stuff. When I took it to the shop he was suprised that a small block block weighed so much. He's a GM racer so he's not hip on Mopar stuff but did race along side Dick Landy and even rebuilt his Dana at the track when one of his guys didn't put his power lock back together right causing him to roach his ring gear. When he took the gear out and saw 5.13 on it he asked if he could get him one he said "No",I have to turn back in to Chrysler. That gear wasn't available to anyone who wasn't Chrysler sponsored.