See what the Audi part number is on EKTA (based on year, engine code or PR number) http://www.partscats.info/audi/en/?i...tgr=1234567890
Note the Audi parts in a text file or Note on your computer and build up a list. The mister-auto site usually has Audi/VW part numbers under the MANUFACTURER REFERENCES (OEM CODES) subheading.
I much prefer mister-auto to ECP these days, but GSF is also OK for some things when they have a 33% off code most weekends but you need to be on their mailing list to get it.