I read that a while back, yet GMC and Chevy are still printing on the window sticker that the heavy duty trucks have a Allison 10 speed. Just look at a 2026 window sticker. Lies and deception by GM, trying to fool buyers. GM has had some serious issues lately, engine problems, transmission problems. Would be hard for me to go dump over 50000 on a new one. Guess I'll keep my 2006 2500HD on the road as long as I can. It's got the tried and true Allison 1000 in it, plus the good ole LBZ Duramax.