There was a little play on the rear most universal joint on the Wagoneer. Pumping grease into the joint didn't fix the problem, so it was time to get dirty and replace it.
The driveshaft came off the car without any trouble.
I could see the grease had not reached the needle bearings in one cup for a while. The channel to this cup was obviously blocked.
A new joint was fitted and filled with grease. Those bolts look puny. A miracle they survive at all, but they have lasted well.
After an oil and filter change the Wagoneer is ready for duty.