1968 Ford Mustang

If you look on the top of the steering box, you will see a screw with a lock nut on it. Just loosed up the nut, and then turn the screw clockwise a little. Then check the play in the steering wheel. Keep at it till you get most of the play out. If you turn it too much, the wheel will get hard to turn. You can get a lot of play that is in the gears in the steering box out that way, but you may still have some play in the rest of the system. Make sure you tighten the lock nut back when you are done.
Good luck