Has anyone heard if GM is going to put a 10 speed transmission behind their gas engine.

I have not heard anything like that. The current 6L90 is a good transmission. I’ve got one of the new 6.6L gas L8T/6L90 combos and it has been good to me for the 10,000 miles I’ve had it.

We have the 10 speed tranny in our 2020 GMC Yukon Denali and love it.Has down hill braking while trailer is attached smooth shifts but time will tell we only have 19,000 miles on the OD..

I have the 10 speed in my 3.0 Duramax and it is a really nice transmission.

I have a 2016 Tundra 5.7 liter and a 2006 Chevy 3500 D-max LBZ, would like to go down to one truck that can do everything.

I would not buy a GM anything without a 10 speed transmission. Funny thing is Ford and GM designed this thing but It is not available on most Chevy Trucks but available on almost all Ford trucks.

My 2020 6.2 has the 10 speed. Great combo.

The OP is asking about the new 6.6L gas L8T engine in the 2500/3500 series. Not the 1500 series trucks with the 5.3 or the 6.2.

I’m not sure why they haven’t put a 10 speed in the 2500’s, other than the possibility that it simply isn’t needed. How many overdrive gears does a transmission need? How close of a ratio do you need on an engine that has a wide and flat powerband?

Based on my experience with both the 6.6L Duramax and the 6.6L gas, 6 gears is enough. Obviously GM disagrees on the diesel end, as they now have the Allison ‘branded’ 10 speed.

Dropping the AFM/DFM and auto stop on the 6.6 gas most likely has something to do with not offering the 10 speed and its overall programming.
Of course, the 6.6 and its 87 octane appeals to commercial owners over the 91 octane requirement of the 6.2.
Reasoning for no 6.2/10 speed in the 2500.

It does not hurt that the OP gets real-time feedback from owners of a GM 10 speed equipped truck.