Went ice fishing last weekend and had the truck in 4wd and whenever I was slowing down my truck would clunk like crazy. Got home and checked it out and I could twist the front driveshaft by hand. The u joints were replaced about 5 years ago because one broke about 150 yards away from the road in 14" deep snow. I don't use 4wd that often maybe 5 times a year so I don't know why the are in such bad shape. Any suggestions for an upgrade or something stronger? Truck is a 99 cummins with Dana 60

 

If you will keep up on greasing it then get a greasable one. If not then they do make sealed ones that are supposed to be "Heavy Duty."