The calipers on the '07 expedition require an allen wrench type tool to remove, I bought about eight different sizes and they are either too big or too small. Can you tell me the exact size I need to remove the calipers?

I'm sorry but no. I have read manuals and they have told me a size and when I got down to the nitty gritty and started to work on it they where totally wrong. I found out the best way to get the correct one is to measure one I am working on from point to point all the way round the bolt and i was correct 99 percent of the time. I have found out that if I use a ratchet and socket with a star it is easier and with less effort. Contact me if you need more help. Thank you
here are some links that may be helpful. http://www.hammerwall.com http://www.tsbdata.com/ http://www.google.com/search?q=belt+diagram&hl=en&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ei=uabQTbDxJZOFtgfR8vXnDQ&ved=0CCAQsAQ&biw=1024&bih=673 http://www.onlineautorepair.net/engine-belt-diagrams.html http://www.2carpros.com/diagrams http://autorepair.about.com/library/pictures/illustrations/bl750a-lib.htm http://www.onlinefreeebooks.net/autos/car/jaguar-s-type-s307-07-harsh-slow-shifts-30-l-v6-vehicles-reprogram-pcm-pdf.html http://www.tsbdata.com/tsb/2000-jaguar-s-type-v6-3_0l.html http://hubpages.com/hub/Serpentine-belt-routing-diagram-2006-Chevrolet-Impala-LTZ-39

A 9mm should fit the brake caliper pins on your expedition.