I have had my truck for 8 months and have had 5 major components replaced to figure out this noise... Axle, Differential, Exhaust, Brakes, and then Transfer-case (not in any order). The only thing that fixed it was the replacement of the transfer-case... It only fixed it for about 1,000 miles and the noise returned. I am fed up with it and am in the middle of GM buying my truck back.
I am wondering if the build date has anything to do with it. My truck was built in September 2018. I've driven several other 2019's as a loaner vehicle which did not make the noise.