[s-cars] awful squeak upon deceleration

[Rokas Reipa]

Hey gang. Started hearing a loud screech/squeak upon letting off the
accelerator in any gear on my 95.5 S6. Sounds like a belt slipping but serp
belt and timing belt are pretty new, along with assorted tensioners, etc.
Also, transmission mounts are new. Any idea on what it could be? The
driveshaft IS loose and is about to be rebuilt/replaced. Any ideas? Thanks a
bunch,

Rokas
95.5 S6