I use a Tekonsha P3 (intertial) brake controller. I was given an old controller with my camper that was the timed type (it puts on more brakes the longer your brake lights are on). THe inertia type measure the decell of the truck and apply the brakes proportionately. Much better in my experience. I also bought the Tekonsha Ford harness (#3035-P). It plugs right in.
On the '02 thru '05 (maybe '06 is the same), the connector is behind the glove box. To get to it, open the glove box, push in a bit on the sides, and it will disengage and swing down completely down. The connector is taped to a wiring harness up at the top left area. Find it, untape it, and hook up your harness. THere is a place up by the firewall over the trans hump where you can sneak the other end of the harness through. I mounted my controller to the right of the steering wheel on the knee kick panel.
Hope that helps.