I know its on the body control module for the F150 and it should be on the module for the F250 as well. The other way to get it is to take the truck to the dealer and have them pull it off the module with their scanner.
Only on 2003-2005 models. i just did this with mine and if you dont have the card in the owners manual you are screwed like i was. The dealership will need to hookup the computer to it to get the code or i my case i had a friend at a dealer help me.