Just did the tow through NM to eastern AZ in strong winds today, with an 8000 lb travel trailer and going the speed limit of 75MPH. The tach barely got below 3000 RPM once today other than coasting downhill into ABQ.
I know it's built to rev like a mother, and I let it do so in the climbs. My wife is always saying I'm abusing it, and I just tell her the engine is overbuilt to handle that sort of workload... but I'd get a diesel if I was buying again tomorrow. I had higher expectations of the gasser with the 10 speed. I figured that transmission would be a great addition to the 6.6L gasser, but the thing just skips the in between gears most of the time anyways. Like if a climb ahead of you looks steep and you kick it down from 7th to 6th ahead of the hill to get it into the powerband, it'll never stay in 6th. It just drops to 5th and revs to the moon unless you are willing to scrub momentum. It has plenty of grunt to pull the hill in 6th but it'll always choose to rev vs grunt.
I used to do this pull with a 2016 5.3L with the 8 speed and that would rev like crazy too, but TBH, it wasn't really any less capable of keeping the load moving. The only place I really notice a difference between the 6.6L and my old 5.3L is getting the load moving at a red light.
This engine is begging for forced induction.