The universal joint, also simply called the U-joint, connects your vehicle's drive shaft to the axle. Over time, this joint gets rusty as the grease inside it dries out, leading to clunking sounds while in gear, drive shaft vibrations and the vehicle shuddering while accelerating. The U-joint is a "cross" or "spider" that is held to the drive shaft by two bearings. When changing a U-joint, the bearings are the parts that will usually need to be replaced.
Raise and support the vehicle's rear end on jack stands.Mark the areas where the joint connects to the drive shaft and the shaft connects to the vehicle, using chalk or water-soluble paint. Remove the drive shaft from the vehicle by disconnecting the U-bolts at both ends and prying off the shaft, starting at the axle end.
Disconnect the C-clips or Spicer snap rings that hold the bearing caps within the joint, which sit in a groove inside the yoke. Pop the C-clips out of the groove using a small chisel or tip punch. Use pliers to remove snap rings by squeezing their clips and pulling them out.
Remove the joint bearings by placing the joint in a bench vise. Put a wrench socket at each bearings in the yoke--one smaller than the bearings and one larger--and close the vise jaws so the smaller socket pushes the bearings out into the larger socket. Remove the cross from the shaft.
Make sure there is plenty of grease within the new bearings. Push one bearing partway into the drive shaft using the smaller wrench socket, place the cross into the drive shaft inside the first bearing and place the other bearing into the shaft. Use the vise to push the bearings all the way in.
Reinstall the snap rings or C-clips; if it won't seat within the groove, strike the yoke with a brass hammer to relieve the tension within the yoke. See that the U-joint moves freely within the drive shaft.Reinstall the drive shaft onto the vehicle. Place the universal joint back in the same position as before, using the index marks you made earlier as a guide.