Saw Mill Would go with 12 volt neg ground later you'll need that for alt. In 30 trucks over 50 years I don't think I ever replaced a light switch. Once your on 12 volt with 12 v bulbs your light switch will work fine dash lights will dim just like before. If you take out your light switch knob (press the button to release it) then put the extention tube on your wd-40 deep into the switch and spray on your way out . This will lube the dry switch internally,most light knobs are shrunk-up where the stainless trim ring will rotate on the knob. Rotating the knob will help knock corrosion off of rheostat dash light dimmer (OK to spray it a little too) Mostly the light switches are pretty durable. Would repair the old wiring harness if at all possible it is double the size for 12 volt service as is ! Also only takes 3 wires to the rear of the truck with an interlocking turn signal switch to do tail,stop,turn signals.
