G80 Diff

Fly-weight spring? Honestly, you need to pop the cover and inspect. But then, if there is a warranty on your repair you may void it. I'd bring it to the last soul that touched it, and see if its covered on a warranty.

Detroit Locker time?

Cheers

My GM dealer "serviced" the rear locker, front differential and transfer case on my '04 Avalanche when it was 3 years old. The bill was a couple of hundred or so. Last fall I decided to do all three myself. The front transfer case drain plug didn't have a scratch on it, and the fluid was filthy. The transfer case aluminum drain plug didn't have a scratch on it and the autotrac fluid was filthy. The rear differential fluid level plug did have wrench marks on it, and had less than 1/2 quart of fluid in the differential. Barely covering the bottom of the gears. The rear cover was the factory original seal, never removed, and the differential and rear axle seals have never had an oil leak anywhere and still don't. My assumption is that the grease monkey who started the job sucked out the rear fluid, got distracted or had another job, and someone else was told to finish it which they did by wrenching the fill plug back on. I was lucky there was 1/2 quart left. My point is that unless you do the servicing yourself, you just don't know what's been done. Usually it's fine, but sometimes.....

Oops, should read: "The front axle drain plug didn't have a scratch on it...."