The procedure for removing and replacing the shaft as described by Volvo tells how to avoid the out of whack geometry. It calls for reinstalling the pieces exactly as they came out. Getting the shaft ninety or a hundred eighty degrees out of phase can lead to the vibrations described here. It gets even worse. The bolts that hold the rear flange to the differential can be of varying lengths to ensure a correct balance from the factory. If you reinstall them in different holes, that also can upset the balance. Once the combination is lost, I don't know of any way to get it back, short of trial and error.

If Dave has had the shaft balanced, then finding the correct combination of flange position and bolt arrangements probably becomes moot. Apparently the balance of these shafts are so sensitive that there's very little tolerance for an out of balance condition.

As for the adjustment of the center support bearing, I found through trial and error that a difference in height of just the thickness of one washer made a significant difference in the driveshaft shudder problem common to these cars during takeoff from a standing start. They're very sensitive.

For more information about this topic, check out the responses in the following thread. There's good information about the drive shaft problem, including the text of a Volvo TSB:

http://www.brickboard.com/RWD/index.htm?id=449299

Robert