On my 2009 Silverado at 13,000 miles back towards the end of 2010, when stopped at a red light, the truck would jerk hard forward. Usually occurs when average breaking is applied and almost always occurs if you stopped the truck quicker. If you apply the brakes, but allow the truck a long time to come to a stop, it doesn't happen. At the time, took the truck into service and they told me the differential needed fluid and whatever they did fixed it. Now its happening again 30,000 miles. When I originally described it to them, mentioned it feels like the truck is downshifting to 1st while stopped, jerking hard. That is the best way to describe it. Truck is going into service Friday for front brake check/change, oil-lube, tire rotation, multi-point inspection, getting the jerking fixed again!