Going back to your schematic at post 80, Yes, your drawing reflects what I did. Both battery voltages to ground were within a few minutes of each other, and the voltage drop tests were done with the both the headlights and interior lights on with the negative volt meter terminal on the positive battery terminal. The increased implied resistance using both your 'lights on' test and my earlier cranking tests are what have led me to check the male and female bulkhead pins before messing with the ingition switch.
