On the backside bottom right hand side of the stock head unit (if you are looking at it from the front), what is that thing that plugs into it? Its a metal type male going into a female in the head unit. Is this for the antenna? Are you supposed to plug this into your aftermarket headunit to have reception? Or is this for the stock cd changer in my trunk?

God my new head unit is giving me a headache!

 

it's the antenna.

the cd changer is the smaller of the 2 harnesses.

 

thank you!