I was recently browsing the web for the best deal on tail lights for my car and i found these and bought a pair. I Thought i share that because my original ones are cracked and Winter is coming don't want to chance having any faults with the tail lights. I believe the tail lights fits these models 2005-2008 Audi A6 or S6 sedan

https://www.europaparts.com/tail-light-4f5945095m.html
https://www.europaparts.com/tail-light-4f5945096m.html