Grinding noise when accelerating past 60 mph

[Walkertexasranger]

Hello, I have a 2002 gmc 2500 HD 6.6l 4wd. Recently I have been driving on the highway and at about 70 mph I’ll hear this grinding noise about where my transmission and drive shaft is. When I let off the gas it clunks then if I  immediately go back of the gas it will make a loud grinding noise again. If I’m driving at a lower speed it doesn’t do this. It’s starting to get louder and sound worst and now it’s doing it at about 60 mph, so I was wondering if anyone knows what it could be. I’m getting several different answers, anywhere from u joints to transfer case to even a bad Emergancy break. 

[04BlackMagic]

Most likely u joints. How many miles of the rig?


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[04BlackMagic]

"On"


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[Supreme Pizza]

I would drop the T-case fluid and look for metal or metallic glitter in the fluid. Then I would grab the drive shaft and shake it vigorously to check for play. Then I would drop the rear diff fluid and inspect. 

[SunShine01]

I’m with a ujoint. In time it will get a bit worse at lower speeds.

Outside chance the pumpkin [emoji316] because you heard a clunk and GM is known to have some clunks in the rear end.


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[Walkertexasranger]

04blackmagic: it has 135k

 

starman8tdc: I shook the drive shaft and it is crazy loose where the u joint meets with the transmission. I’ll see if I can attach the video

166C9EF5-218B-42AD-B831-9370CFE0E7C9.MOV

[txab]

Time for u-joint replacement. Might as well replace others on that shaft while you have it out