You have to look inside and see what's going on before we say full rebuild.
It's past the point of oil change if the wheel is grabbing it toast metal on metal is what's going on.
Edit; Rubber plug in the diff cover.
If all the clutch discs fail/bust up to pieces on one or both side's there is a chance the c clip will fall off the axle, if it does fall off that will let your wheel and axle depart from the diff.
Last edited by merc225hp; 04-25-2013 at 12:42 PM.