Hello guys. New here. I own a 1992 1500 4x4 w/350. My problem is this. In O/D at about 70mph my truck wants to viberate, shake whatever you want to call it. What happens is when the engine gains RPM's (to pass or go up a hill) it viberates/shakes. It stops when I release the gas, or push it a little more. At a steady speed it doesn't. Now I looked at the universal joints and no slop or slippage. Any suggestions????