Volvo Repair: 2004 V70R vibration, viscous coupler, 2004 volvo v70r

Question
Hi, I recently purchased a 2004 Volvo v70R, which has a vibration that is difficult to pinpoint, but seems to be coming from the rear passenger-side wheel.  The vibration only occurs between 65-70 km/h (40-44 mph).  When I test drove the car prior to purchasing it, there was no apparent vibration at any speed.  However, when I picked up the car from the dealership after having some work done to it prior to purchase, the car exhibited vibration at the speeds noted above.  The only differences in the car between the test drive and my picking it up after purchase were: a new set of summer tires was mounted on the original Pegasus rims and the passenger side seal on the bevel gear unit was replaced (which I think required removal of the front axle?).  At first I assumed that one or more of the new tires was misbalanced, but I subsequently purchased a new set of peg rims and I got the new tires mounted on those and the vibration remains.  New winter tires on the old pegs also vibrate.  I checked all CV boots and they seem fine.  I don't hear any squealing or grinding from any wheel, just the vibration.

Reading forums has provided the following possibilities: Driveshaft/Propellor shaft unbalanced; bad wheel bearing; bad engine mount(s); bad viscous coupler; bad CV joint or U joint.  One possible suggestion to diagnose would be to drop out the propellor shaft to see if the vibration continues.  If so, that would seem to point to the wheel bearing or CV joint.

What do you think?

Thanks in advance.

Answer
Jeff, on these AWD nightmares its usually the Viscious coupler that is the culprit but you would hear a noise.  Are you hearing any noises?   Since you just bought the thing, bring it back to the dealer and have them remedy the situation especially if you bought a warranty with the car.  Roger