The dreaded drivetrain clunk

[kmaroman]

The truck in question is my 2005 Silverado 2500hd 6.0 4x4. 
 

For years I’ve had the slight clanking when changing directions and taking off but here recently it’s gotten quite noisy.  At first I thought it was just the rear parking brake, because after using it one day it seemed to stick enough to cause some squealing noises.  Had a similar issue with a 1500 years ago.  well I kept pulling up on the lever and I think it loosened because it hasn’t been squealing any lately but it’s started clunking. 
 

I had my truck up on stands today and decided to check parking brake but the noise wasn’t coming from it. The noise was coming from the drive line, so I started looking at the u joints.   well they looked like garbage(260,000miles and there probably the originals) but I didn’t see any slop in them.   The noise seemed to be coming from the transfer case tail shaft but it also seem to travel down to the rear end as well.  
 

I had heard some weird noises I couldnt isolate up front recently and it got me thinking that’s probably what it was and the sound was also traveling down the driveshaft making me think it was the parking brake.  
I’m going to go ahead and replace the u joints see if it helps and I guess putting grease inside the driveshaft is suppose to help quiet it all down.

 

does this sound like typical gm clunk or is my transfer case going bad ? 

[swathdiver]

Probably the slip yoke.  The chrome finish can wear off causing the clunk.  You can grease it or replace the output shaft.  Do the cheap stuff first.

[davester]

If you have a 2-piece driveshaft, maybe also check the center support bearing and grease the slip joint there.