Rear end hopping: driveshaft?
 

I have an '07 f250 fx4, still under warrenty (extended). Been to the dealer, found no problems. The problem: Rear end seems to hop/vibrate starting @ 40mph-50mph. Seems like driveshaft is out of balance to me. Tires have been balanced and rotated; axle is true; and rims r fine..... Problem is amplified when put in neutral @ the above speeds (no load); and can also be felt more when decelerating @ these speeds. My truck only has 40k miles and is in great condition. It is a recent purchase, one i'v been wanting for a long time. I think the driveshaft is out of balance/bent?

Thanks, Sturgie

Thanks for everybody's help. This is a great site that seems to help out many people's problems. And to think i was going to pay for online technical help. Ha! I got all the answers right here! Thanks again.

Sturgie