My '84 245 has rather suddenly developed a nasty vibration in the rear end. It starts at about 25 mph and gets worse as vehicle speed increases. At low speeds (say under 40 mph), if I depress the clutch so that the car is coasting, the vibration is not as severe as it is when power is applied. However, at highway speeds the vibration is constant. The entire rear of the car feels like it is going to shake itself apart.

Bad rear ujoint or am I looking at a potential rear end rebuild? How to tell? If the rear is bad, is it better to have a shop rebuild it or just swap out the entire axle for a boneyard axle?

The car has 400,000 miles on it and I know the rear has never been touched aside from draining/replacing the fluid. I have had the car since '90 and have changed the fluid every other year.

Tried swapping tires front to back. No change.

Thanks,
Chuck