2003Z71

Had the same issue, have the dealer change the transmission fluid to the new version. I also have an Range module to stay in V8 mode all the time. Problem solved

Just call your dealer service department and they’ll know exactly what your issue is and they’ll change the tranny fluid. I just had my 2018 Denali with the 6.2 and 8 speed get a complete tranny fluid flush and change. I have 28000 miles on the truck and noticed the issue arising around 20k. I bought an AFM delete by Range and that seemed to help the problem between V4-V8 mode for a while and it progressed to get worse. I too had the rumble feeling primarily through the steering wheel and it also felt like the truck was not running smooth even on new pavement. I would say that the tranny fluid made all the difference and solved the issue with an exception. When I initially drove it off the dealer lot I did not plug in my AFM Range delete and got on the highway the rumbling still came into play in V4 mode. I was pissed. But then I pulled over and plugged in the Range. Problem solved so far. It’s running perfectly with smooth shifting, no clunking, no vibrations. I think the problem is a combination of the old tranny fluid and made worse by the V4 mode. Invest in a Range, sucks that you have to pay another $200 to get rid of the issue but V4 mode sucks anyway. And I did not notice any difference at all in fuel mileage running full time V8.

Purchased last week. Clay bar , polish, and ceramic coated.

That is one sharp looking truck!

Just got my truck set up to where I wanted it. Bought my track last Dec and was completely stock until 3 weeks ago. Took me forever to decide on the setup and I couldn't be happier. Fuel Crush 20" wrapped with BFG 285/55/r20. Did a 2.25 level in the front absolutely no rubbing and plenty of clearance. Added Corsa Touring this weekend and Corsa performance intake. System is awesome. When Cruising there is no drone and quiet as stock, when you get on it it just sounds amazing. Perfect system in my opinion.