[sector95]

U-Joints can fail in many ways....they don't always get loose and sloppy. If these are the original joints then they are probably at the end of their useful service life. Sometimes the joint can be tight....but internally the grease has hardened or the rubber seals on the bearing ends have failed (or both) and allowed water into the joint...the combination creates a messy goop of old grease and rust that will eventually sieze the joint...and when that happens you run the risk of destroying the yoke assembly (where the u-joints press-fit into the driveshaft and transmission slip yoke). The squeaky sound you hear might be the bearings of the joints failing due to lack of lubrication.

If you have the single drive shaft you *must* pull the driveshaft, clean and regrease the slip yoke (the part that slides into the splined tailshaft of the transmission) on a regular basis (maybe twice a year or so). Failure to do this can cause some driveshaft clunks when moving off from a stop. Greasing allows the drive shaft to move in and out of the transmission tailshaft spline freely as the rear suspension moves up and down. Nobody likes to do this because it requires you to remove the driveshaft....and it's kind of a pain to do. After you clean the slip yoke splines, use some good, viscous water proof grease (I use Bel-Ray water proof bearing grease which you can find at most motorcycle shops) ....normal chassis grease tends to thin out too much and you don't want it to mingle too much with the tranny fluid.

Mike
98Sierra