I have an 86 Bird w/5.0 engine. I need to know what to do to upgrade my rear end in the vehicle. I don't know the ratio/type that is in the vehicle now. I do know that from dead stop to hard acceleration (off the line) I feel a jerking and sort of wheel hop like the rear is locking/slipping. Could that mean the rear is broken? The vehicle still drives and does not do this if you start off sloowww. Thanks, Jay