A lot of dif cars had dif ways of tightening belts. usually there is a arm with a slot in it, (that is where the tension is made) that the alt is bolted to. You have to look on the side or under the alt, there will be another nut and bolt somewhere on it, loosen that and the bolt on the arm with the slot. Use a bar of some type to wedge under the alt and pull to put tension on it and tighten the bolts back up while holding tension on the belts. That should be about it.