[s-cars] Vibration from right wheel when backing up?

[Brian DeWyngaert Jr]

S-heads, I sent my vehicle in the shop to have them help diagnose an
issue that started after they performed the replacements of both my
outer CV boots.  The issue is that in reverse if i turn the wheel to
the right more then half way to lock, i begin get a shuddering that
seems to source from the right side of the car.  Tech called me back
today and said the axle shaft was shot and needed to be replaced.  To
which he said that the OE part would cost him round $530, he said he
had found one Aftermarket part the was close to $385 for the left side
and he stated he could not find a replacement part (save for the OE
one) for the right side, and that since the part was rare so I didnt
have alot of options for sources.

Does this diagnostic sound reasonable to you or could this be
something else.  Again the shuddering is only noticed in reverse,
which the tech claimed is a "feature" of audi axle shafts.
The tech is also saying that he is noticing slight vibration if the
wheel is turned to the left.  I dont recall feeling anything but I
will have to test it out tonight.  I just find it odd that not long
after they replace my outer CV boots that this begins to occur.

Cheers,
Brian
94S4 NoVa