I've searched for people having the problem elsewhere, and really haven't found much on it. At 60+ MPH my truck will start to vibrate/rumble like crazy. It usually is intense for a little while, fades more toward the back, then comes back up front and is intense again. Then kind of just continues like that getting worse with speed. I had this problem before and after I did the following: 1.5" lift with AC upper control arms New torsion bars New leaf springs New shocks New wheels and tires New U-joints New ball joints New center link New tie rods Alignment (obviously) Also I have manual hubs that always stay unlocked unless I'm offroad, so the front driveline isn't moving at all. Like I said it feels like it's mostly coming from the rear of the truck and then kind of varies in intensity. I really feel it in the seats, and sometimes it'll even shake the dash. The steering wheel is pretty much unaffected. Mechanic suggested wheel or tire problem, but for the same problem to carry over after new wheels and tires plus all of the above, I'm a little skeptical. Anyone have any idea what this could be and how to fix it? I'd like to do some longer road trips to experience some of the wheeling outside of my state. Even now some of the places I'll frequent are about an hour away and it's tiring dealing with the vibrating the whole way there.