If you're going from a 7.5 to 8.5, you just need to have a driveshaft shop chop 1" off and rebalance it. What trans are you running and where you located? I have the driveshaft from my 8.5" swap that I would sell for extremely fair, but not gonna ship it.Picked this 8.5 up. Gonna clean it up and paint it. And thanks the oils rear end out. Does any one know if I have to use a different drive shaft?