70 Duster Ignition Switch Test

I would recommend you test for voltage with everything connected. A ohms test is not conclusive because a connection can have continuity and not carry a load. Imagine a battery cable with a single strand of wire. It would show continuity but not carry a 150 amp load of the starter. Search for a wiring diagram of your system that will show what wires have power with the switch in each of the positions. Also, it would be helpful if you stated what the nature of the problem is that you are wishing to diagnose.