One new old stock Leistritz brand rear muffler assembly, part number 105-937 or factory part number 437 253 609B.  This is a new old stock item and has developed surface oxidation from storage.  This fits:

Audi 5000 Turbo 1980-1983

                                                           Before purchase, be sure to check                                                           
 >>> VEHICLE COMPATIBILITY NOTES <<<
  to verify fitment on your particular year/make/model.