Front Diff noise

[upstairsdave]

Greetings, I have a 2004 Yukon AWD with 104K miles that makes a whirring sound when I every so slightly accelerate and decelerate, going for drive to coast sides on the gear mesh, indicating to me that the ring and pinion gears may have the incorrect gear clearance or are worn out.
I have heard that the aluminum case halves are the culprit causing the carrier assembly to be out of line and the diff needs a rebuild of new bearings and possibly gears and case halves. I also replaced the right front hub bearing assembly as it was noisy. I should probably replace the left Hub bearing so I don't have to worry about it failing away from home.
I'm just want to be 100% sure that I don't have a transfer case issues and not a diff issue.The vehicle does make a louder rumbling sound when I am decelerating to under 20 MPH to a stop. Almost sounds like cupped tires but the tires are brand new Michlins.

A diff. rebuilder wants $1000 to rebuild it and that's just the bearing and seal replacement. I'm already $1000 into new tires on this ride and kinda feel that it'll nickle dime me to death. Yeah, I've got the clunk when going from drive to reverse. That sounds like ring and pinion clearance issue in the rear too. U Joints seemed fine. Add up all the rust and really needing to replaced the rear splash shields on the brakes and replace all calipers as the bleeder screws are rusted away to nothing.
Appreciate your help
Dave

 

[bucket]

Your clunk while going into drive is nothing worry about and the play back there probably comes mostly from the carrier/spiders, rather than the ring/pinion.

The noise up front, have you checked the fluid level? Has the noise been getting worse over time?

 

[silverado13]

also id put it up on stand and play around with it and see if you can feel any abnormalitys like resistance or anything