Need advice please! Can someone help!
 

I apologize if this has been asked before.
My 2008 Mark LT has the stock 6disc/mp3 satellite radio and I have purchased the ford Nav/ 6 disc version which also came from an 08 Mark LT. I know I'll need a gps antenna and maps but......

I haven't swapped radios yet but my radio has 2 plug sockets in back and the Nav radio has 3 plug sockets. Small, medium and large. Not counting antenna ports.

The question:
Under the rear drivers side seat is a long black box which I'm fairly certain is a subwoofer as I can feel a speaker type thing under it and it's pumping base for sure!!! I don't get it. Radio has 2 plug sockets and subwoofer is there and working.
Does this mean that my truck has the audiophile system? If so, would one of the sockets back of Nav radio be for the sub?

Thanks in advance.....philip

Breakdown:

Large (24 pin plug) is power and speaker connections
Medium (16 pin plug) is for changers and data connections
Small (8 pin plug) is for the subwoofer

Many units do not have the 8 pin plug.

I had given my vin to one of these ford nav guys from eBay and was told my radio has 2 plugs in back. He was wrong.
My radio did have 3 plugs in back which makes perfect sense because my truck has the factory subwoofer in back and it pumps!
I purchased a factory nav radio on eBay from a private seller and it was plug and play.
All I needed was a nav antenna. A very simple swap.
It came from the same vehicle, 08 Mark LT like mine and all works perfect.
I'm very happy.

Thanks to all forum members.
This site is very helpful and I've learned a lot from reading the posts.