Break a few ring gear teeth, shock the driveline, you can roll a sprag.... and the drum can explode. Friends low 11 sec car did just this. We didn't know what caused it until we tried the pull the axles out of it and they wouldn't come out. Couple years later we saw another car break an 8.75 on the launch. The guys were going to throw a set of gears in it and go. Convinced them to pull the trans...where they found the sprag was a mess. Does it always happen? nope... prior to my friends car exploding I had broken a set of gears, and we put in another set and away we went... knowing what I know now there is no chance I'd do that again without a teardown and inspect.