Thanks guys, I'll research... It vibrates, sometimes feels like the rear sometimes feels like the front of the tranny... thats why I thought U's but it'll vibrate for a few seconds and.or I'll let off the gas to get it go away... it happens very sporadically and doesn't really happen at all if you drive on it HARDER... driving lightly causes it most of the time... as I think about it, more like driveshaft vibration, but its' getting rough