Upper arm with standard bushing: A > N
Upper arm with beefier bushing: B > P
Beefier bushing used by allroad, and cabriolet and Q5 for some years

Lower straight "track arm": F
Lower curved "guide link": Q > AD
So I assume you're asking about the guide link, not the track arm. The Audi catalog seems to have no application for the rev AA, only that it was dropped and use Q instead. Q of course now being replaced by AD.