Rear deck has 3 speakers. 2x 6x9 ("Subs") and 1x 3.5in mid.
Center channel in front is the same 3.5in that is in the back.
Front Doors are 5x7 or 6x8. Some 6x8's do not fit. The speakers that say 5x7 or 6x8 on the specs usually fit.
Front tweeters in the a pillars are custom, but you can fit a 1in tweeter if you have fabrication skills.
The rear doors are coaxial 5x7 / 6x8's. Since they have a tweeter sharing an axis with the midbass Ford counts them as two speakers each.
So you have 4 speakers when counting the front doors and tweeters, 1 for the center channel, 4 speakers for rear doors, and 3 speakers in the rear deck. That makes 12.