When I turn the wheel like under 5 mph the wheels like jerk in the back, I replaced both u joints one was bad, when I pulled the cover all the gears were in tact but it looks like the driver side clutch material in the rear was burnt up, i can hold one wheel and spin the other forward with some pressure, does that mean its bad?do they sell just the clutch kit so I can put everything back the way it was and just a new crush collar?