Just replaced two U-joints on Goliath (M1081). Was pretty easy job.
Reason for pulling the joints: I upgraded to the 3.07 diffs and started having an intermittent vibration around 55mph. FYI, I'm using a GPS speedometer for now. I put 18oz of antifreeze/water in each tire and that didn't seem to help, so pulled the joints that I disassembled when doing the differentials. Rear driveshaft had a cup that made some noise and vibration when reassembling the joint after removal. Probably a bent, dented or broken needle.
Note to all doing driveshafts and U-joints for them: make sure to use the proper tool to press in the U-joint cups! Driving them in with a hammer, while convenient, is not a good thing especially when they are a tight fit. Spend the $100 for the Tiger tool or the clone. Then go spend another dollar or so for the proper size bolts. The bolts that come with the Tiger tool are a size too large, something like 3/16" UNF versus the necessary 5/16" UNF. I'm guessing the size though - take one of the clamping bolts out and take with you to the store to make certain you've got the right size and thread pitch.
Same with pressing the joints out - use the proper tool to disassemble the joint, and don't forget to pull out the grease fittings (there may be two of them on each joint). Don't hammer on driveshafts or joints...
Still need to grease the joints, then test drive...