kev93p-up

This weekend my wife and I went out to her familys 38 section ranch in NE New Mexico. One section of dirt road about 35 miles long to and from the ranch was in such bad need of repair I thought it was going to shake our teeth out. A couple of days after we got back I realized that when I would accelerate at about 60mph the truck would vibrate badly, but only when on the gas. When I'd push in the clutch the vibration dissapears. I also noticed a slight rattle when taking off from a stop like something's loose. So I crawled around under the truck and checked the drive shaft but it was all secure and looked fine. I did however notice the tires are cupping a little and need to be rotated. Has anyone else had this problem? Solutions, ideas? Do you think the tire cupping cause that problem? I seems to me the problem is somewhere in the drive line. Please help.

Flamedx4

REally hard to guess. The on-the-gas thing rules out most things including the tires. Maybe ujoints? Had the same problem with a lifted TJ, when I put an angle finder on the output shaft and the pinion the angles werent' good, I removed the transfer case drop and the angles were near perfect and the vibration on the throttle went away. Huge difference.