Front parking lamps, front and rear side markers, tail (running) lights, license light and dash lights are all from the same place on the headlamp switch.
At the rear behind the license plate there is a black ground wire bolted to the underside of the box. At the fron,t follow the negative cable from the battery... it should be bolted to the body before continuing on to the intake manifold. It's possible the cable was replaced by a previous owner and this important body ground removed. You can make up a 12 gauge ground cable from the engine to the body sheet metal. Make sure it is solid and making good contact.
Last is the lighting switch. The running lights should come on at the first lighting position and stay on at the second position when the headlamps come on.