ok now ive just read through this whole thread and im still lost, ive got a factory tape deck/stacker setup, ive got the plug with the 4 wires that someone said was for satnav plugged into my headunit, so ive got 3 plugs in the head unit and one empty socket, i also have a round socket 5 or 7 pin i think, with nothing plugged in to it. there was also a frequency expander in there that the plug broke off when i was poking around. and there is an extra plug in there going no where. can anyone shed some light on this??