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?

George wrote:

> 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?

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.