I have another loose u-joint, 3rd one in 6 months same location, front prop shaft to front diff. Could I have bent the house and opened it up when installing a previous u-joint? What else would cause failing u-joints? The diff seems ok, but the TC front output flange has someplay. The truck drives smooth with the new u-joint, but after a long ride it starts to vibrate every so slighty and then if I crawl under the truck I can feel the loose front u-joint. Btw, I did all four a year ago and the rears are still fine.