HI, NEW MEMBER ON HERE IN DESPERATION,LOOKING FOR AUDI BREAKERS OR MAYBE A MEMBER WITH AN O/S/F HUB CARRIER/STEERING KNUCKLE FOR A 2011 A4 B8 3.0 TDI QUATTRO,MANAGED TO FIND ONE BUY BOTTOM REAR ARM BALLJOINT IS SMALLER  AS WELL AS TRACK ROD END ONE BEING SMALLER AND TAPERED WHERE MINE IS LARGER BUT SAME DIAMETER TOP TO BOTTOM.

                                                       TOM

Hi Tom welcome to the forum you'll find the members on here are a friendly and helpful bunch. I'd recommend you search eBay but include international sellers. This is what I'm now having to do with my 21 year old a6 c5. 

Welcome to the club….

eBay and other online places like AUTODOC are your friend. I’ve replaced both of mine just because of the pinch bolts seized and couldn’t risk being part way through the job and have a U/S knuckle and no car so bought new ones. I think around £120 ea….most the sellers are clear on the two different size ball joints….I think they are the same as some Q5 also. Be sure to use a quality separator as the hardened steel inserts have been known to pop out of the aluminium (if you were refusing any ball joints)