GC1009

Longtime lurker, first time poster - I've got a 2016 Yukon XL with the 6.2L. I was having a similar issue with a clunk when shifting out of park and have noticed what I describe as a hard shift or hesitation on occasion when shifting from 1-2 and 2-3. The dealership said no issue with the transmission that they could find, but replaced the motor mounts - they are a piston/shock type assembly vs a rubber damper. The motor mount replacement seems to have solved the clunk when shifting out of park, but the hard shift is still there. I've been looking for the TSB that talks about swapping out the transmission fluid multiple times if you're in a high humidity or coastal area as the fluid that was originally used apparently attracts moisture into the fluid.