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Discussion Starter #1
Since I got the truck, there has been an audible knock/click/clunk type sound coming from SOMEWHERE under the truck, it could be anything, transfer case, diff or trans, I have NO idea.

It happens intermittently when driving (at upshift and downshift) or when changing gear selection into or out of a drive gear. It is sometimes SO loud, I can hear it with windows up, climate control and radio on.

Currently has 32,300 and has the G80 rear diff.

I plan to have the dealer flush the transmission, transfer case, and both diffs at 50,000 miles, but have not thought it necessary until then.
 

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Sounds like something loose in the drivetrain. I'd start by insepcting ujoints, pinion bearing, and the like to see if there is any slop anywhere.
 

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Discussion Starter #3
yeah, its definitely gear slack. thats precisely what it sounds like, gears slapping together.

I have been under there about 5 times inspecting everything and have found nothing out of the ordinary. besides the noise, all operation is 100%
 

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Sometimes diagnosis is about eliminating possible causes. Can you be specific as to what you've inspected and eliminated as a possible cause? Have you opened the differential up, yet?
 

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On my dads 02 chevy pick up it is doing the same thing. he took ti to the dealer and they said there was nothing that they could do for it and that it is a common problem.... Sounds like a bunch of BS to me but u mihgt have better luck where u are at.... GOOD LUCK
 

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Discussion Starter #6
No, I haven't opened the diff yet to check it out, I really have not had time recently. I've basically just gotten under there and looked for something out of place...but found nothing. And since drivability is perfect...it continues to be back burner. Being that it only has 30k, what on earth could already be wrong?

Is anyone else here experiencing this?

As far as diagnosing, I'm pretty new to these trucks, so maybe someone could let me know what I should be looking for? I can open the diff case...but I don't expect it to be any less than normal.

Main problem is, the truck is out of warranty as of Sep 2007, so my biggest worry is that I DO find there is something wrong.

Well, maybe this weekend, whenever I have time off work, I will get under there and check some stuff, maybe just find out where the heck it is coming from specifically so I'm not on a wild drivetrain goose chase.

Might have to hit up some mission impossible moves to be under there when the sound is happening, but I really don't want to be on one of the road trips I've planned for this year and have this become more than something audible.
 
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