drive line noise

["Richard McIntyre, APS Engineering 223-2379 ML05-2/E45" <mcintyre@eng.pko.dec.com>]

My quattro with 160K+ is beginning to make a whining/scratching sound at low
speeds - at least it can be heard only at low speeds (<30).  From the front
seats, the noise seems to be comming from under the shifter/hand brake area.
My fear is that the center diff is going south, but then again the drive
shaft bearing could be at fault.  The diff oil has been recently checked.
The drive shaft bearing seems to have a lot of play, but I can't remember
how much it had when new.

I had to have the diff oil seals replaced a few months ago as they were
leaking.  No problems since, and the noise has just started.

Anyone have any ideas?   

Richard