If you have a rear light on and a front marker light I would think your headlight switch is the problem, easy, or the wiring harness is worn contacting a live wire somewhere and powering the lights, not so easy. Try pulling the connector of the back of the headlight switch and check if the lights go off. If the switch is 40 years old it could be giving up the ghost.

The hazard light switch could also be at fault. It operates with the key off or on as well, maybe just enough voltage jump to light up a front and rear light?

My ignition switch, in the off position, was allowing just enough voltage through to get a current flow from the battery but not quite enough to operate the fuel gauge, gen light , park light etc. I was chassing wires for hours before I disconnected the ign switch and discovered my problem.