The adjusting screw is on the top of the steering gear in the center of it. Loosen the locknut with a wrench and tighten the screw with a screwdriver. After you tighten the screw a bit, hold the screwdriver while you tighten the locknut back up so the screw doesn't move. If you have jack stands you can get the front wheels up off the ground and check the freeplay by turning the steering wheel after you adjust it. It might take a couple of tries to get it just right. If you adjust it too tight it will be hard to keep the truck driving straight because the wheels won't return to center by themselves.