I have a 2009 GMC with a 6.2 litre matched with 6 speed tranny. I have taken this truck many times to the dealership with a tranny that makes all kinds of wierd noises. This truck is 17 months old I have 159000 km, and when it shifts with any weight or torque to it makes an awful noise like a clutch slipping or the sound of brakes when they are way to hot this only happens when it is shifting from 1st to 2nd gear now some times it will just shift hard or when you are slowing down it will jump a gear. The dealership says that they have reprogrammed it they cleaned the mass air flow sensor (not sure how this affects tranny?) and they say that they can not make this happen when they take it for drive. So i am not sure what to think of this tranny warranty is up in 1000km i am going to take it one more time to hear the same story and when warranty is up it will have to be replaced at my cost funny how it all works any ones advice would be great i searched all over the internet thanks