U-Joints bad?

I have a 99 silverado, 4x4 extended cab. It has 5.3L and 4L60E transmission. I recently noticed some strange symptoms. When I come to a stop, it sometimes feels like a klunk. Its almost imperceptable and kind of
feels like something "letting go." It doesn't happen all the time, maybe one in five. Sometimes, when I leave from a stop, I get a very light klunk. Today, with the window down, I was driving about 10 mph, and it sounded like something rubbing. Like the noise you might hear with a piece of gravel stuck in a tire tread. The driveshaft doesn't appear to be loose or have unusual play at the u-joints. Can the u-joints be bad and not have excessive play in them? Is it more probable that the clutch pack in the limited slip (G-80) rearend is about to fail?
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George wrote:

The g80 is not a limited slip, it is a locker which locks at a specific time, there are no clutch packs. I've had u joints get squeaky and noisy without being able to feel play in the drive shaft. Buy both and swap them, they are cheap, just watch out they are sticking chinese made ones in the boxes now.
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George wrote:

Well it could be U-Joints. Could also be the slip yoke on the transmission end of the shaft. They are know for those symptoms when the lube gets out of them. There are a bunch of TSBs on it and GMs final solution was to replace the yoke with a high nickel plated piece. The grease is MUCH cheaper.... I would pull the shaft, check the joints real close (if in doubt replace them with a GOOD greasable joint) use some GOOD grease and coat the inside of the yoke good and reinstall it. Not difficult to do. Oh and while you have the grease out you might want to pull the intermediate steering shaft out, clean it and relube it before it starts making a clunk when you turn.
--
Steve W.
Near Cooperstown, New York
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