I'm at a loss I've got an 06 dodge 3500 5.9 4x4 mega cab it's an automatic I've been chasing a vibration I've done hub assembles, ball joints, u joints, tires, went to one piece drive shaft in rear, changed tires, did upgraded steering plus more and I still have a terrible vibration from about 53 mph to 66mph. Thoughts? I've could have bought another truck with the money I've keep throwing at this

 

Rotate the tires, does the vibration change/move?

 

They been rotated and I've also put a new set on and didn't change it whatsoever

 

So it's not wheels/tires causing it. Do you feel it thru the seat, or the steering wheel?

 

Through the seat more but the steering wheel a little bit

 

When's the last time you had the tires balanced? I would also check the rims to see if they're bent anywhere.

 

Likely something in the rear then. Wheel bearings in back?

 

I've done all of that stuff, could the transfer case bushing or seal be a problem??

 

Try some tests to determine when you get the vibrations.
When getting the vibration, try some s turns, does the vibration change turning in one direction or the other?
When getting the vibration, gently apply the brake, does that change the vibration?
Get someone to drive next to you and observe your truck when getting the vibration, particularly look for wheel hop or wobble.
Look up death wobble and see if you may be getting early signs.
Other areas to check: brake rotors, suspension bushings, eng/trans mounts, drive axle for being out of round.

 

Ok all is good there but was going to ask if a motor mount would do it?