If I'm correct you'll need the code from the sticker on the top side of the stereo. Use the release clips to slide it out of the dash just enough to view then enter it in to one of the Ford code calcs found here http://ajacker.pbworks.com/f/carradiodecoders.zip
Worked for me when I had to change the battery on my ST170. Hope that helps
AJAcker
May 2009