Driveshaft vibration

[GP Thompson]

My 2003 XC90 has developed a vibration that seems to come from the driveshaft. It is most noticeable at highway speeds but only when accellerating suggesting it is only when power is being transmitted to the rear wheels. When not accellerating (ie coasting down hill) it disappears. If I select Neutral it stops.
It feels like something that rotates is badly out of balance. Any ideas?

[BigXC90]

Could be an angle gear problem too. Same symptoms.

[GP Thompson]

Thanks for that comment. Do you have any advice on how to confirm that it is the angle gear? If it is what does the repair involve?

[GP Thompson]

Problem was the CV joint. The culprit was a ruptured rubber boot.