Mainly eBay. There are ones in America on eBay and it says left hand front, but then says “for a left hand drive” and not sure if that makes a difference!?
My 2004 RS6 has just failed its MOT and one of the things it failed on was its front left hand shock absorber. I have looked on line and its no longer available from Audi. I can find lots of right hand side absorbers, but no left!!? Can someone please HELP! I have the part number 4B3413031R