SO short and simple, I have this issues of a moderate vibration when I let off the gas at highway speeds only, it goes away after a few seconds, but then when I put my foot back on the gas the same thing, goes away after I catch back up to speed. Any Ideas? All fluids good in tranny I was going to check the rear diff tomorrow.

 

Sounds like a bad universal joint on the rear driveshaft. Raise the rear wheels off the ground. If equipped with 4WD, select 2WD. Engine off. Trans in neutral. Grab the rear driveshaft with both hands near the universal joint. Make sure the U joint cross is horizontal. Push up and down on the shaft, rotate it 90 degrees and push up and down again. Should be no movement. Do the same thing on the other joint.

 

Is it happening at a particular speed? Or is it just related to speeding up and slowing down

If it is just at a speed band it could be something out of balance (Had similar issue with mine a few years back. Only at highway speeds, right between 65 and 70. Turned out one wheel was ever so slightly out of balance.)

 

Well its only at highway speeds no other time does it do that. It feels like its from the rear end. I will have to lift it up and check those u joints. Thank you for the responses.

 

If the U joints are good Check front hubs or wheel bearings. I had a similar problem caused by tires not being balanced. So foot off the gas pedal then it starts? Coasting vibration?

 

Yes foot off the pedal and it starts then goes away then starts again shortly when I put my foot back on the gas.