The front one is more worn than the rear. They were done by a professional driveline shop ~25K miles ago. Not sure the brand. I've been greasing them regularly with Redline CV-2 The rear U joint is a conversion U joint, as I changed from the stock chrysler 8 3/8 axle to a Chrysler 9.25, which has larger Yoke. Anybody know off hand which conversion U joint this would be or how to determine which? I was wondering at what i consider to be the short lifespan of the joints. I suspect the driveshaft might be out of balance, or my rear airbags and ability to change rear ride height puts more stress on the U joints. I did recently put about 1600 miles on them with about 2 inches more rear ride height than level, and shortly after the road trip is when I heard the low bearing type rumble on Decel sub 15mph which once before, proved to be the U joints. I also had issues with redline CV-2 not being compatible with the grease whcih came in my ball joints. It degelled. i wonder if grease in teh U joints was also partially from improper lubrication. I've never done U joints myself. These have the innner clips. One more question is that my drive shaft is pretty rusty. if I take it out and to a driveline shop for balancing and new joints, is it worth me treating the rust and painting it myself, or pay them to do it? Any Idea of cost? I've no idea if the driveshaft is really out of balance, only a suspicion due to the short life of the U joints.