Recalling, been awhile so this may be a bit fuzzy, my 2011 Silverado 1500 came with a 100k mile power train warranty and nowhere in the owner's manual schedule of maintenance activities is there a reference to change tranny, differential, or PS fluid. The schedule is inclusive to 100k mi. I guess they went full syn and got rid of those hassles.
Don't recall any HD notes as I don't use mine in HD situations so I skip over those parts of the manual. I was pulling my boat yesterday, not that big of a load and tranny has "Tow-Haul" button extending the shift points to higher rpms, and checked the tranny temp at 167F max in 90-95* weather. It does have a tranny oil cooler, like some tractors have hyd. coolers and I guess some have oil coolers too. My 6530 has a hyd cooler.