Try your dealer. Mine sells to me wholesale. I have purchased many cars from him and he treats me right on parts and accessories. Ask. It can't hurt.
You're looking for Ford part number 5R3Z-1130-BA Try this: http://www.fastfordparts.com/ Type the part number into the "Search by Part Number" area of the page. Or you can google the part number. I ordered mine from the internet this way, paid about $65 for them delivered UPS. My dealer wouldn't sell them for less than about $80.
I'd still check with the dealer. Mine doesn't charge me shipping no matter how large or heavy the part. That alone can save you big bucks at times.