Still have low freq vibration (95 A6Q)

[thejimrose]

collapsed rear diff bushings?  the one in my a4 clunks like crazy on
aggressive shifts. assuming the a6 has a similar mounting deal, you
might be metal on metal on the front diff mount. that might cause such
a noise.

might also be collapsed rear suspension bushing? heck even the exhaust
might cause that if it was rubbing / knocking on something. although
the noise seems to be more consistent than if it were caused by metal
on metal rubbing..

my first thought was CSB, if you had the cv done maybe the part is
flawed? maybe the propshaft lost balance [dropped, weights fell
off..], if nothing external is wrong then i would suspect something in
the rear diff..