A 3-letter code may be stamped directly onto the housing, usually on the driver's side near the front differential flange.

Identifying Audi A6 gearbox codes (often three-letter codes like KJC, TXD, or 0B5) is essential for sourcing parts or diagnosing issues. The is via the vehicle build sticker, usually located in the spare wheel well under the boot carpet or on the first page of the service booklet. Common Audi A6 Gearbox Types & Codes

Common in later A6 models and quattro variants, often identified as ZF8HP . Manual: Examples include 01E or 01X 6-speed units. How to Find Your Gearbox Code