My ex boss who was a pretty serious drag racer, asked me one day if I knew anybody who had a 904 with the GM bolt pattern. His son, who was the manager of the parts department thought we were both a little off thinking such a thing even existed. I made a call to a shop and knew if the shop didn't have one, he'd know where one was located. He had one and $1000.00 later my boss was happy. Put it behind (after a lot of modifications and HD parts we were developing were put in it) a 500" Steve Schmidt Pro Stock GM. Broke into the high 6's at 200 MPH in his BA/A race car.