From a stop when I hit the gas there is a groaning coming from the rear end or suspension?? My old truck a 2000 z71 did the same thing and now I have a 2005 z71 that started making this groan when I first accelerate. Sounds like its comming from the leaf springs? Not sure if its my rear end or u joints? Also the driveshaft has a little play in it I don't know if this is normal. When the truck is in park I can turn the driveshaft 1/2" in either direction.