Mine MY04 X did NOT come with this installed and I'm planning on adding it. The kit itself is only like $30 something dollars and it plugs into the head unit behind the dash...not from somewhere behind the vehicle. The AUX input jack itself, as everyone has indicated, may be located anywhere your imagination takes you...your installer would just have to run the wire from the head unit. I'm not sure what the fuss is about? An AUX input of any type would be either of RCAs or a stereo mini (like the solution BMW use). In either case, it's just an interface connector that you'll need to get a cable and hook it up to your source (portable player).