Several recent GMPP warranty pricing responses indicate an AT4 requires a $350 lift surcharge on top of the warranty price. The GM warranty we purchased for our last AT4 Yukon did not require this surcharge. Does anyone know if this is only required if it was purchased with an aftermarket lift or aftermarket wheels and tires, or do all AT4 Yukons require the surcharge now? To my knowledge, the AT4 Yukon doesn't have a 2" lift like the Sierra does. This particular unit has the steel sprung suspension without air too.