after a trip to a transmission specialist to chase a ghost that was thought to be a bad right front wheel bearing and axle support bearing (since we had that side of the drivetrain unassembled, why not change it too...), i ultimately ended up at the volvo dealer on a hunch i got from some friendly posters on v70xc.com. it seems that i had a bad lateral motor mount that allowed the engine to tip/roll in the engine compartment with car body roll. compounded by inertia while turning/cornering to the left only, i was getting a low level grinding or gear noise from momentary front drivetrain misalignment when the engine moved relative to the front right axle assembly. $300 US later (parts & labor) and i was off and running like new. of course, that doesn't count the near $1000 in trial & error with driveshaft and tranny specialists. guess i'm lucky it was that simple. all seems well for now and my volvo technician says that i have no consequential damage with other related drivetrain components.
185k miles and on my way to 200.....
:)