Hi,
www.autoscout24.at , in case you want to buy a whole V8 to part. Otherwise, stick for Ebay or "Teilemarkt" here on the platform.
Regarding the ECU: We had the situation once that we tested not one, but a couple of ECUs and _all_ were death. Sincerely I thought it's not the ECU, cause that would be a strange fortune. By accident I got a ECU from an S6 monthes later and tried just for fun - and guess what, it worked!
I know really hardly any cruise control ECU factured between 1991 and 1994 still working. Most people head on for younger ones (used until 2000 or even longer, all compatible from ALL Audi models) or changed back to one from the 3,6 V8, but this requires solding - or at least re-patching.
Keep it in mind, but check the vacuum and the switch first.
Regards
Bastian
