I don't want to hurt fealings or step on toes but with his set-up IT WILL BREAK!

Any diff can break with enough abuse.

I speak from experience 3800lbs 69 Roadrunner with a 10" slick, 5 speed, Cal-Tracs, around 650lbs/ft torque. I have broke axles, bent things on a Dana 60. The 8 3/4 would have destoyed it self long, long ago.