Pin weight is a big factor along with ensuring your rig is level behind the truck. I had the same issue with my 2015 Sierra, and, to a lesser extent, my 2020 DRW - trailer pin weight of 3,200+/-. I went with a FlexAir pin box with the 2015 Sierra, and it eliminated 95% of the chucking. It was too long for my 2020, so I went with the RotaFlex, and it did the trick. I like the RotaFlex much better than the FlexAir, as it is a simpler design, and you don't have to worry about adding air all the time.