To my knowledge, there is no OE part number for just the pads. However, you can find them all over ebay, Amazon,all the major Audi suppliers (Ecs, FCP, EuropaParts, AutohauzAZ) probably sell them.
I was wrong about the major suppliers but Blauparts sells a valve cover gasket kit that includes the pads and everything else you need.
See the post below for additional info.
https://www.rs6.com/showthread.php/3...l=1#post271144