where is anti-theft module

Hello,
I'll do better than that; I'll send you a link to AutoZone's repair guide for your E150.  Here ya go: http://www.autozone.com/servlet/UiBroker?UseCase=RG001&UserAction=beginRepairGuide.  If that doesn't bring you there, simply go to http://www.autozone.com, enter in your vehicle, then click "Repair Info" and "Repair Guide" in the left-hand menu, and you will get to it.
Best of luck!
CarGrrl