MN Yukon

https://www.google.com/amp/s/gmauthority.com/blog/2019/08/tsb-seems-to-fix-8-speed-automatic-gm-transmission-problems/amp/ I believe all of the part numbers are outlined in the special service bulletin in this article. 18-NA-355. Its been revised a couple times, just make sure ya get the most recent recommendation of the mobile 1 fluid. The water retention of the old fluid was a key problem. I'd check, the dealership may do it for free. Good luck! I'm getting mine done on Thursday.

Ive known my tech at the dealership for years, he's the only guy I trust and hes the guy other techs shut up and learn something from. Hell be tearing into mine on Thursday 1/6. Im curious about all the questions you've raised. I will say that when he replaced the ball joints on my 09 he did it as a complete assembly. Not sure if that was convenience, parts availability or best practice. Funny thing with that truck is I had multiple components blown, never noticed a thing. In my new Denali however I'm gonna need a chiropractor and a dentist. Anyway, I'll try to get the lowdown and I'll let ya know what he says.

I know its a year old, but I'd love to revive this discussion. Just bought a 17 XL Denali. It has the P0711 code, shudders in most/all gears, and was filled with the same faulty hydroscopic fluid from the factory, same defective trans temp sensor and harness, causing all of the same failures. I have the 6.2 mated to the 8 speed just like other covered vehicles, but for some reason GM is only covering the 15 and 16 models under a special service bulletin. Also omitting 5.3 engines. Tech at the dealership tells me the new fluid has completely fixed every case like this he's seen. The fluid retains water. The water on the clutch causes the shudder. They know the part (fluid) is defective, but refuse to cover for all vehicles involved. GM says, If it walks like a duck and talks like a duck... Ill need to see the vin. Sorry, your vin says your not a duck. That'll be $2500 please. Its maddening.

I just bought a 17 XL Denali with 80k on it. Traded in my beloved 09 XL Denali (rode like a dream before and after various suspension parts were replaced) This new Denali rides like a U-haul truck. Previous owner put bfg ta/ko tires on it, but there's no way that explains the level of bone jarring from this ride. I have no doubt there are multiple blown components, but question is what do I replace with. No way am I sticking with magnacrap just to revisit 20k later. Overall while there are some features I love, im a bit underwhelmed with some things that seem to have gone backwards from the previous generation.