They performed the TSB trans fluid change and also reprogramed the TCM on my 2015 Denali with the 8 speed, this would have been around 48K-ish miles. Surprisingly it took care of the issue and currently at 99K and the shudder issue hasn’t came back.
I do know sometimes it can be an issue with the torque converter and some guys had that replaced also. Dealer did not replace the torque converter on my vehicle and the problem was solved.
I have a 2016 that has this same issue and I am pissed, they are changing the fluid but are not changing the filter. I am being told the old fluid is collecting moisture and that is why they specked out a new fluid. What pisses me off is not changing the filter because they are too cheep and don't give a crap what happens to your 65K vehicle down the line when you are off warranty.
No if ands or but the filter is contaminated with not only the old fluid that collected the moisture in the first place but the milky crap that is created when oil and water are churned together. I was hoping to get 200K miles out of this truck and hand it down to my daughter but this POS will never make it without being a money pit.
Its getting to the point where its not worth buying a car under 100K in miles and paying big money for them just to have a warranty isn't worth it because GM and the dealerships don't care about you.
Previous issues on 2016 Yukon XL:
Cam @ 22K mile
Power running boards@25K miles
heated sets never worked right and don't really get hot on high ( always been there and deal keep telling me it is what it is.
AC condenser @ 45Kmiles fought with GM and dealer over this.
Tail lights 40K miles
Last 3 fords no problems
last 2 Jaguars few issues the dealer was fare to awesome.
2001 Yukon the deal asked that I not bring tis truck back to them.
2009 rusted out on all the door seams and under hood before I could pay it off.
I will never buy GM junk again !!