I have a 2021 Denali HD with the Duramax/Allison combination with about 33k miles and I’m starting to feel a shudder between 45 and 60mph. It completely disappears when I shift into neutral and coast and starts back up as soon as I shift it back into drive. There is no difference with tow/haul mode on or off and seems less noticeable when towing. About 20k mikes are towing a trailer at about 9000 lbs. Dealer has no answers so was wondering if anyone here is/has experienced the same issue and what was the fix.
Thanks
