91xjgawes

I know this has been covered over and over but i figured I would start a thread to see if anyone can help me in figuring out this problem. the truck is a 15 2500 4x4 with 38k miles. No modifications other than a ranch hand bumper on the front and the torsion keys turned slightly to make up for the heavy bumper. since I have owned it the truck has had a vibration so to speak. It is audible and you can feel like through the gas pedal. It starts right around 60 mph or so. It seems to dissipate when going past 75 or so. At that certain speed; around 60 you can ease into the gas and feel the vibration and hear it. It almost feels like something is out of whack. I sometimes compare it to going over rumble strips or a really bad section of road. It is most noticeable on the interstate where the road is smooth. I have replaced u-joints in rear shaft. Put a brand new set of Nitto ridge grappler tires that have now been balanced 4 times. i am at a loss, any insight would be very much appreciated. thanks wes