Quattro123.com

Chuck's Strut bar.

Chuck's bar is made to use the Audi Ur S4/S6 tower braces

found in the newer chassis car.  There is a left and right bracket.

These are found in ETKA on the A6 suspension page. Part numbers on link below:

Nearly all the info you need about the 10V and 20V 100/200 is also shown with alternatives here:

http://www.quattro123.com/Audi200StrutTowerBraceMOD.htm

Chucks strut bar.  Audifans.com 200 20V list

Peter S and Mike S also helped me obtain a list of part numbers and a magazine reference for comparison.

Thanks to Mike S and input from Peter S, they found a write up in the Quattro Quarterly winter 2004 (page 85?) AFAIK

...........and some parts numbers from the Family Album.
Strangely Version 5 doesn't list an S4 from 1992 - 1995.5
A6/S6 from 1996 up does. Listing the A6 produces the items.
The parts aren't mentioned until the end of the parts numbers like in a notes listing.

If you want to upgrade your 200/100 chassis rigidity by installing an Audi
factory part from the "ur" S/4S6.  As Bernie says: this is a tower brace not a strut brace.............FWIW.

Deciphering the code:
4A0 is the body type
"805" =  section 8 sub type 05
That isn't always accurate, but it is true most of the time.
PARTS:

Left Mount:   4A0 805 635
Right mount: 4A0 805 636
BRACE:      4A0 805 645A