re: Truck Rear Differential question

Ford's limited slip rear ends are garbage. Instead of paying Ford $1000 to replace garbage with more garbage Personally I would find a local 4x4 shop that can replace it with something like the Eaton Detroit TrueTrac which is a fully mechanical LS differential. It will be much stronger than the stock dif and will probably outlast the truck unlike the clutch pack eating LS rear ends Ford uses. You will be looking at around $600-650 for the parts, ~$500 for the differential and another $100-150 for the install kit (Bearings, bushings etc). Throw in a couple of hours of labor and you will be ahead a couple of hundred bucks and never have to worry about the rear end again.