8 3/4" How Strong?

ch1ll said
The stronger the rear axle, the more its going to weight. The more weight, the more poorly its going to handle.

There is a certain amount of accuracy to this but the way you out it, it seems over stated. There is additional weight but not at a serious penalty. Drag racers can attest to this. Any additional weight can be wrote off as a reasonable penalty worth having in exchange of durability. The weight is unsprung.

For autocross it would be best to back off max torque and horsepower and build a engine with good torque matching the rpm it comes out of corners at so it pulls hard and match the lightest rear axle that will handle that power.

While an advantageous move, this is really hard to do from a new guy point of perspective. Changing conditions would have constant changing of equipment. Knowing the car and track as all as the engine power curves are where this all starts never mind the equipment being used. Just where this area of to much power is can not be determined by internet chatter.

Murry did say, first time with big power….