As previously mentioned, the Sport Trac does not come with a power tailgate lock, and it is not an option from Ford.
There are numerous companies that sell electric tailgate lock actuators. They are basicly the same as the electric door lock actuators but typically use a different mounting bracket and linkage. All you need to do is to thread two wires under the vehicle and over to the passenger side rear door sill. Under the sill molding is a wire trough with a bundle of wires. two of the wires are the lock/unlock wires for the doors (colors vary by model year). Just tap into those wires and your tailgate will lock when you lock the doors, and will unlock when you unlock all the doors (press the remote unlock button 2 times).
Cost of electric tailgate lock kits vary from $29 to $89 but are all essentially the same and price is not an indicator of quality since the actuators are pretty much all made in China, so they all have about the same reliability.
I have purchased some new electric lock actuator motors for as little as $3.00 on ebay which is probably much cheaper than you can get one at a junk yard. Just be sure to get the 2-wire kind for your Sport Trac and NOT the 3 wire units. 2-wire units just reverse the polarity (+/-) while 3 wire use the third wire as a ground.
...Rich
