Downshift Noise in 90 Quattro

[Sperry, Peter A -Syntegra MN]

In my wife's newly acquired 1990 Audi 90 Quattro (4 Door), when I downshift
or if I drive in, say, first and then back off the gas so that the engine
slows it down, there's a strange noise that comes from just rear of the
tranny.  
It sounds as if something is scraping on the drive shaft, because at slower
speeds I can hear it turning.  I don't know how to best explain it, but
someone out there I'm sure has had something similar.  
I took it in to get it aligned this morning, which might be the problem, but
I'm curious if anyone has had the same sound?

Peter
'88 5KSQ
'90 90Q20V