It could be that the tires are out of balance. Mine did the same thing and with these big rims and tires if they get out of blance they will vibrate like crazy. I would check that first as it's the easiest. Also make sure all the lugs are tight maybe you have a rim coming loose or something. Deeper it could be coming from the axle, transmission or transfer case? If it only has the vibration when you acclerate then maybe it is joint related. Did you check to see if there is any slop in the u-joints.

Good Luck!

 

If you drove through mud and left it park overnight, the mud or even ice/snow will cause it to be out of balance.

Driveshaft is another possibility. If they have done differential work on it they may not have aligned the driveshaft up correctly with the differential key.

Being you can't feel it in the steering wheel then I'd check the rear wheels first. go underneath the D and look at the rear rims and see if there is anything accumulated on there. Also it would be worth to put a wrench on your lugs and make sure they are tight.

Then check if they've done any work to it. Or if you got it from a certified dealer, PM me your VIN and I'll tell you if they've done Axle work.

Good Luck and keep us posted.

 

Check tire balance first, then work from there.

 

I had a similar problem with mine and it was that the ujoints were shot, all changed all good now.

 

I would agree on the u-joints/driveshaft causing the vibration.

 

But start with checking the tires/cleaning the back sides of the wheels.. cheapest and easiest fix.

 

It is not likely a wheel/tire imbalance issue. If it was, the vibration would still be there regardless of throttle input.

 

not neccessarily. Depending on where the imbalance is the centrifugal force is noticeable at certain rpm/speed/throttle input. Hence the vibration at a certain Speed. If the imbalance is off more toward the center then you would have to travel at a faster speed than if it was on the outside of the rim.

It is easy to test Ujoint vs balance. Get to the speed that produces the vibration the worst and turn on your cruise control. Then push your tow/haul button and when the rpms increase notice if the vibration changes. If it does then it is a ujoint or driveshaft issue. If it doesn't change then I say tire/wheel balance issue.

 

I just bought a used 2004 Limited 5.7L. I am having the same problem. I took my pry bar out there and poked around and found that there is a bolt that holds the top of the front diff to a mount. Mine is missing allowing the front diff to wiggle.

Probably not your problem, but get under there with a pry bar and check things out.

Good luck,

Sims

 

Good job finding the issue.