I'm trying to reinstall the factory stereo and amp to bring it back to bone stock. I've unplugged my old Pioneer head unit and removed the aftermarket harness. In the attached photo there's a Ford plug, this plug is behind the glovebox and the Pioneer had the speaker wires going into it. Now that I'm trying to go back to stock I can't figure out where this plugs in? I've felt all around in behind the HVAC controls and can't see to find another matching plug that it goes with? Where's it's mate?