Truck vibrating above 60 mph

[5.0gray90']

my 01 4x4 ranger has an annoying vibration when cruising on the interstate. its almost as if im driving on a rumble strip. it doesnt feel like a wheel/tire issue, more like a drive shaft out of balance or something. i was planning on getting a different rear driveshaft from the local salvage yard, but i figured id post a question first. anybody experience these issues or have an idea what it could be? i feel it mostly in the seat, but the vibration can be felt throughout the entire truck. also, what year drive shaft interchange with mine? its a 2001 4.0L auto, 4x4, extended cab, one-piece shaft. thanks!!

 

[kcm1582]

Have you checked the drive shaft? You might have worn out u-joints, or a rear tire out of balance. There's a lot of things that could cause a vibration, I wouldn't change the drive shaft because of a vibration unless there was obvious damage.

 

[5.0gray90']

i noticed the vibration when i first got the truck and i replaced both u-joints in the rear shaft, then i rotated the tires front to back and still have the same vibration. i've also changed rear end fluid and inspected the ring and pinion, along with adding new friction modifier. still have the vibration

 

[trail B2]

Where any of you u-joints bad? Did you take the drive line apart if so did you make sure to line up the u-joints to each other that will cause a vibration.

 

[GoodOld85BlueBalls]

What kind of tires are you running?

I had hell with a set of BFG's that the belts seprated in the tires and caused it to bounce with a light vibration. Took months to get the tire dealer to do something about it. When they changed one tire it all went away.

Is there any cupping on your tires?

If it keeps vibrating I say you should take some girls for a ride with you.

Hope you find it man.

 

[bilzy7]

Well if you swapped tires front to rear and vibration isn't coming from a new side it front, then it isn't a balance issue.