You need to remove the rear quarter trim panels around the side windows and the rear seat back frame. After you remove the "head rest" there are two screws at the top and two at the bottom of the seat back frame. To access the lower two you need to remove the seat bottom as well, use a medium size flat tip screwdriver and insert it between the seat bottom and the floor support. Sklide the screwdriver until you meet resistance, pull it out slightly and move it a along a little further then push in. This will release the seat bottom latch. With all these items remove the rear deck panel will slide right out. Its a pain in the butt to remove all these items, but neccessary if you don't want to break anything more. Ford was stupid to put the speaker in from the top, but Ford does stupid thing like this all the time. P.S. I'm a Ford dealership tech.