Check for a broken axle shaft first. Jack up the rear wheels one at time, and try to pull the tire/wheel assembly toward you. If an axle is broken, the wheel will move toward you, at least a short distance. The wheel will also spin easily. Last resort- - - -pull the cover plate and spin the wheels by hand after jacking up the rear end. That's a lot less work than dropping the torque tube unnecessarily. If the axles are good, THEN drop the torque tube and inspect the U joint.
Jerry
