Mike262

2021 sierra 1500 with 3.0L duramax. 40k on yhe truck. Driving down a smooth country road, flat surface, cruise set at 55. The truck will be in a high gear. When I get to a little grade in the road, right before the truck wants to down shift, it fells like the transmission starts to shake. Not a vibration but a small shake. Has anyone experienced the transmission shaking? It will shake enough that a passenger that does not ride in the truck often will notice it.