It just bolts diagonally from one cross brace with a long bolt. Other end at the back uses a threaded rod so you can tighten the special long bolt with the loop that allows you to put a padlock on it. There should be a u shaped part on it the goes up and keeps the tire from sliding off. Bear to lift into place. I think this one is installed wrong but if it works, hey.
http://67-72chevytrucks.com/vboard/s...d.php?t=351141
http://67-72chevytrucks.com/vboard/s...d.php?t=502836
You can adapt the winch type from a later year to work with ease. I had one until I moved the tank.