I was backing my 2005 Chevy Avalanche with the G80 with the 342 gear ratio factory locking diff out of the garage Sunday and it made a popping noise. I stopped and went forward a few feet and everything seems to be fine now, no noise since. I have read on a couple Chevy truck forums that this isn't anything to worry about with the G80 locker. Truck has 172,000 miles and probably has never had the diff oil changed, I bought it used 1 year ago. I did drive it a little in the snow a week ago and it did lock a couple of times while climbing my inclined driveway but no problems until Sunday. I'm going to change the diff oil soon. Any thoughts on why it made the noise and reccomendations on diff oil? I'll probably use synthetic gear oil. Thanks
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