I have a 4wd drive ranger with 20,000 miles. When I engage 4wd high it feels like i'm hitting speedbumps. when it first started it was hitting hard now it has eased up a little. i drove it in the snow and when i would feel it the rear tires would break loose and the truck would go sideways. I have the truck at the dealers now but i would like to know if anyone has seen this before