There is so much in this thread I don't know if I should even bother.

A friends 85 Mustang that he raced in a Street STOCK class running only 12.3's when it broke it's first 8.8, with traction lock, when it twisted the end off a stock axle, the rebuild upped it to a spool, c clip eliminators and 31 spline axles with more gear , this was behind a 5 speed running slicks and launching at 4000 rpm.

Fast forward to 2013 , different mustang , now a V6 5 speed, running low 13's , Ford Motorsport 8.8 with 3.73's, the trac lock lasted one short season , now it's got a tru trac in it, still with slicks and still launching at 4000 rpm , axles should be next ??? He has his original rear as backup , it's his daily driver ...

Dom , you can do all the bracing , axle bearing change , heavy duty caps you want to the 8 3/4 , pick whatever size pinion you want because in the end they are ALL THE SAME SIZE where the outer pinion bearing slides on ... you still won't fix the weak link ... RING AND PINION teeth breaking off .