I have a 75 El Camino and need to change to alternator and power steering belts. Is buying a tension gauge necassary or just suggested? I know they aren't expensive but I don't want to buy one if I don't have to.

The way that I was taught to tighten belts was to have no more than a half inch of play in the belt when moved up & down. I don't know if this is proper or not, but it has served me through the years. Jon