causes? high torque, sticky tires, heavy car, tall gearing....if this a 904 trannny? not uncommon behind a 360 or larger motor...

in my 3950lb 5th ave that I had 3.55's and an A500 in behind a 360 and 255/50R17 BFG KDWS's, the TQ had cracks starting at the corvers of the pump drive slots. never hung the weight of the tranny off of it, but had a fair amount of heavy acceleration, and those tires hooked pretty well....