My headlights won't work, taillights work, dash lights work although the high beam indicator light stays on, just the headlights don't work.

Check (multimeter) that you do or do not have power to the lights, and at fuse block and even at the dash switch for the headlight wires after in on position. May be a loose/burned connection there or in between. My 65 had the floor mounted high beam button, check for power there with dash switch on. If no power to button after dash switch is on, change dash switch out and think about relay mod too, but before changing out parts look for shorts as this can cause a no power too, if no power from high beam button but has power to it change it out if both have power before and after check for relay mod if ever done before the relay could be bad. The dash switch on these older trucks pull a full 12volts threw it then by the time power gets to lights they may not have but 9volts left to run them and are dimmer then they should be without the relay mod to pull the 12volts away from switch, without relay mod this puts a burden on the older switch and can burn it out or wire at it for headlights so this may be what is going on, if the dash switch is bad or the problem a new dash switch will solve it but could happen again and a relay mod can be done to correct this and also give the lights a full 12volts.