i have 2000 silverado 4x4, 5.3 vortec.
truck has developed a clunk coming from trannie's tailshaft area, where the output shaft is. there is no clunk when you move trannie up and down. but if you move driveshaft up and down, it clunks inside the output shaft housing - or what i called tailshaft.
same happens when you get on a bumpy road - clunk-clunk.
of course, slip yoke also makes that infamous rub noise when taking off, but i am used to that one. I i am not concerned about this rub, we'll pull slip yoke out and lube it next week)
any ideas on the clunck? one piece driveshaft.

 

sound's like a tailshaft housing bushink any leak's there

 

no, no leaks at all.
what is tailshaft housing bushing? clunks inside of the transmission "tail".

 

there is usaully a bimetal bushing that the drive shaft slip yoke slide's into it provides a wear and seal surface for the yoke .

 

well, surprise!
we had driveshaft dropped today. clunck is coming from the output shaft. when we grabbed it with fingers and moved up and down, it'd clunck inside the transmission extension.
so, we said - hell with it, turn up music and be happy. then, we packed extension and slip yoke with that miracle grease from GMC.

well, then after i went on VERY bumpy roads and railroad tracks, and more bumps. NOT ONLY THAT ANNOYING RUB AT TAKE OFF IS GONE, BUT THAT CLUNCK IS GONE EITHER!!!!!

my theory is: when slip yoke splines went rusted and started making that rub at take off they, also, would catch on splines in the output shaft and drag it, causing clunck, when driveshaft was bouncing up and down on bumps.

well, whatever the cause is, it's gone.

BUT HONESTLY, I FELL THEY SHOULD HAVE PUT DRIVESHAFT SUSPENSION BEARING/BRACKET TO STEADY DRIVESHAFT NEXT TO TRANNIE.