Audio Systems: 2001 lincoln navigator stereo, lincoln navigator, couple hundred

Question
I just got a 2001 lincoln navigator, and I am pretty sure that the sub is blown. Do you know how I take the sub out and instal a new one? I know you have to remove all the side paneling, but everywhere I take it they want a couple hundred bucks to change it, not including buying a new sub.  

Answer
sometimes is not the sub but the amplifier  you have to check
you have to remove all the side panel from the back to the passanger door   once you see the box with the speaker and amplifier you can remove all 4 screws and the speaker is not going to come out ( WHY FORD HAVE TO DO THIS??? )
THERE IS 1 MORE SCREW IN the back of the box  that holds the magnet so the complet box have to be remove from the vehicle  for you to take that single screw from the back

amplifier are $90.00 and the speaker $85.00 from oemautosound.com

good luck