1982 Dodge Rampage starting problem

I saw what you replaced, did you check for voltage, anywhere? What switch did you replace/ neutral switch or ignition switch?

At the starter, the red wire is battery voltage, hot all the time. The brown wire goes hot with the key in the crank position. When the relay is energized, voltage on that brown wire.

Any testing at the starter make sure the tranny is in park or neutral and the parking brake is set. By the way, did you try cranking in neutral?