Parking lights not working

The headlights are a different circuit. The headlights only power comes from the splice in the ammeter wire and goes right to the light switch

I'm not familiar with the fuse layout in the older cars, but if your tail lights work, it's not the fuse.

This leaves the bulkhead connector, always a suspect, or the feed coming out of the light switch (connector) to the park lights, or the switch itself.

On the newer cars, when manufacturers went from "no park" in headlights to park / tail / head all staying on, all "Ma" did was to move the feed to the park lights right at the swtich over to the tail light terminal.........still used the same switch.