Guys I read every thread on this issue and still having problems. My truck has 90,0000 and never had a vibration issue before now. I had a near crash situation and ran off a dirt road around a turn and the right side took a pretty good blow to the rear tire. Bad enough that it split the side wall of the tire and even broke the rim. Replaced the rim and bought 2 new tires. This is when the vib started. Since then I replaced both rear drive shaft universals. Done extensive work on the front end. Replacing both front axles and universals, the drivers side front wheel hub, and ball joints. When completed I had a front end alignment and all 4 wheels balanced again. The vibration is only at high speeds and is like a light switch coming on at 65 mph. The vib is not coming out by going faster in fact it gets much worse. To the piont I'm scared to even take it up to 80 mph. I tried changing the rear dirve shaft position to all four ways it could bolt up and not making any difference on any position. The vib is not really in the stearing and can be felt through out the whole truck. My next move will be to take the front drive shaft off and see if that changes any thing. Then I guess to have the rear drive shaft balanced. I'm running out of time and money and getting no where. Since I have a 50 mile commute on interstates driving 64 mph is getting pretty old. I hate to drive it but at 64 you can't tell any thing is wrong. Any ideas would be greatly appreciated. Thanks to all