No other is listed as optional across the entire M5U 8sp / Hydra-Matic 8L90 - L86 6.2 fitment.
Meaning - 2015 Hydra-Matic 8L90 (M5U) Eight Speed RWD Automatic Transmission for Chevrolet Silverado, GMC Sierra, GMC Yukon/Y Denali and Yukon /Y Denali XL, Cadillac Escalade and Escalade ESV.
Optional 3.42s seems to be a 5.3 and or 6sp AT choice. Same for all other ratios ie 3.08, 4.10 ? etc.
With the far greater gear spread - probably not needed and or desirable @ least @ this time.
They got a nice 'official' bump on some of the SUVs ( City and Combined ) and if examined in detail, more than likely something around 3.5 - 7.0 % on the ones where the over rounded official estimates did not change.
The farther into Combined and or Highway or better you go the higher the gain is likely to be.
Some will have a good bump in City cycle and below; some will not get as much although still with some sort of positive improvement very likely.
Idling is idling - for the most part.
Also..... uses a new Fluid or @ least the Corvette M5U does. I'll take 10:1 it is very similar to what an 8HP uses.
If correct, then, that is going to be an eye opening experience for some..... compared to D6.
We shall see. Maybe they found a less expensive fluid.
Currently not listed for a Standard Cab of any kind - or for at least Sierra or Silverado. ( Can't remember if both were checked.)