Home Depot. The Huskey 13 & 26 piece kits include a 9mm Hex Key.
9mm hex key front and 7mm rear
Try Sears, Napa, Snapon, or my favorite Matco.
Front caliper: 9mm hex socket (special), Rear: T-45 Torx.
9mm hex
On most 2006 Expeditions, the front calipers use a 9MM hex bit while the rear calipers use a 7MM hex bit. 9mm hex bits are not easy to find as singles and will usually only be found as part of large metric hex bit sets. .
Fiochi
A regular hex key, or a hex socket with a ratchet.
The size is 9mm hex. It needs to be long enough to reach the recessed caliper bolt.
I have the Key, But use a Bike Key for a Schwinn Bike with Hex nuts (12.99) It's a Y shape, and has 3 of the sizes needed. Try any better bicycle shop for this key. I think they call it a hex wrench or Service Wrench (Although it's NOT a wrench) Better yet go to your local sears and buy a hex set that will fit onto your cordless drill it takes them off and puts them off 10Xfaster.
9mm hex socket bit
To remove a hex screw, you will need a hex key or Allen wrench that matches the size of the screw head. Insert the hex key into the screw head and turn it counterclockwise to loosen and remove the screw.
To remove and replace floating caliper mounting bolts. 3/8" and 8mm hex bits are used for General Motors vehicles. 7mm and 1/4" hex bit are used for Ford. 2003-2006 Ford Expedition use the 7MM hex bit. 7MM hex bit does not work on a 2006 Expedition. Looks like it requires a 9MM, the only one that is not included in my hex set. On a 2006 Expedition Limited, the front calipers use a 9MM hex bit while the rear calipers use a 7MM hex bit.