Clunk in the driveshaft

[missinglink]

Ive been getting a clunk in the drive line when I come to a complete stop, and again when I take my foot off the brake!! My dad advised it may be a bad u-joint. When I got under the truck this morning, I can see where the u joint goes into the transfer-case, it appears that there is about 1/4-1/2 inch of shiny metal w/no grease, and when I shake the drive shaft, I can feel the slack . Truck shifts smooth and I've only used 4wd a few times, very lightly in snow. I'm hoping this is a easy thing to repair, and would appreciate any helpful advice.

Matt

2003 GMC 2500hd 4x4 ext. cab, gasoline
2005 Audi S4 Quattro

[DmaxMaverick]

Welcome aboard! This is not an uncommon issue. Your U-joints are probably fine (no indication of failure from your current symptom). The drive shaft needs to be removed, and the transfer case slip yoke spline (the internal spline of the yoke) needs to be lubed with grease. Lithium grease works best, otherwise use a molybdenum grease (synthetic base for either is always better). If you do this with the grill pointed downhill, you shouldn't lose much, if any (depending on the grade), fluid. Uphill may dump a bunch. Lube it and reinstall. U-bolt torque is 53 ft/lb if the nut has an attached washer, or 101 ft/lb if it doesn't. Should be good to go.