I have already broken a side gear in the Spicer clutch diff in my 8 3/4. All it is is peppy 6.1 and a 6spd in my 72 Dart. The S60 housings are lighter than factory 60 housings. Im thinking a Dana is in my future with the big Ford ends for the big non adjustable bearing. Cornering is harder on stuff than you think. After this year I hope to find a buyer for my 8 3/4.