Behind the panel that covers the fuel reset switch. So looking down at your feet from the passenger seat - right foot, that side panel down there comes off. Tucked up behind that panel and up under the dash is a black box with a sticker on it. That is the code. I also found this too...
Where the code can be found
This code is located on the owner's wallet card in the glove box
Is available from your authorized dealer via scan code
Is marked on the computer module
Computer Module location
1995 thru 2001 is located in the jack storage compartment in the rear of your Explorer. First remove the panel to the jack storage compartment. Towards the front of this area you should see a metal box this is your auto-lock module(way up front next to your rear left passenger seat). On the back side of this is your 5 digit code factory preset code. It is hard to get to. To see it you will have to loosen, pull, use a flashlight or a mirror but it can be done.
2002 thru 2007 is in the right panel behind the middle row window. It is below the seat belt mechanism. You have to pull out the top plastic panel off, then loosen the lower panel to be able to see the face of the computer module. The code is on a sticker on the face of the module.