I just finished chaning both u-joints on the drive shaft and once I got them apart I could tell that the front one (Transfer Case to Drive Shaft) was bad.The front and rear u-joints seemed solid while on the truck but I had the clunking so I knew I had a problem. It sounded like it was coming from under the drivers seat more than the rear axle. One of the four caps seal failed and allowed some grit and dirt to get into the needle bearings. I had a little trouble getting the u-joints out of the yokes until I just hit them harder with my hammer. I had at first tried to press them out using a large C-clamp. I am just glad to be done and not have the clunk anymore.

 

Glad you got it them ujoints can be a b*tch!!!!