It amazes me that anyone would use a GM rearend in anything with any torque or horsepower. Even in general use the GM 10 (and 12) bolt is prone to Failure. Most failures involve pinion coming apart or axle breakage resulting in severe vehicle damage. By the time you modify a GM rear end to survive, you could have saved time and a lot of money and updated to a Ford 9" inch and be done and forget about it. The 9" is simple, heavy duty, and easy to maintain and service. There are hundreds gear or diff upgrades availible. The 9" is just the standard of the hot rod industry. Case closed.