On Edit:
*** I'll leave this for anyone who may happen to find this information helpful on another project, but I realize this was in the OBS section. For the OBS, disregard. The information below pertains to the superduty chassis.
On my 550 I had to install the steering wheel with cruise control (the airbag/horn module has nothing to do with this) and the clock spring that had the additional wiring built in for the cruise functions. The clock spring is simply the little round plastic swivel behind the wheel itself that houses the ribbon cable that allows the wheel to turn while you have wired circuits in that wheel. It is easy to install fwiw. The necessary harness plugs are already in place under the dash at the base of the column now.
Aside from that, you must address the brake pressure sensor that will probably not be in existence on your master cylinder, but the plug for the sensor will be on your chassis harness usually either clipped near the distribution box, or laying on the inner fender liner.
To disable it you must close this circuit. Either tap in a sensor and plug it up, or just plug in a sensor and lay it on the fender or simply jumper the plug with a length of wire.
The existing brake sensor in the cab on the pedal will allow the cruise to kick off as intended even without the redundant sensor outside. And if that were to fail, the service brakes should pull the truck down enough to slow/stop it even with the cruise still engaged, so I didn't pursue it any farther.
Mine has been working fine for a year or so now. SOOOOO much nicer for towing on the interstate.
Good luck.... nothin to it when you get down to it.
