Dealer states there is no fix and all Chevy trucks have this problem. They shimmed the leaf springs due to a tech bulletin but this did not fix the problem. Another dealer stated they could not hear the problem on a test drive, I could not get out of there parking lot without hearing it. It is progressing. I am looking for a fix.

Update from Dec 10, 2022: 94,000 miles and still clunking away in the rear end.