Thanks for the help. It explains a lot. My understanding is that my 39 once had a voltage cutout and not a voltage regulator. The voltage regulator came along in 1940. I'm wiring my 39 for a 12-volt generator and regulator and using a general-purpose fuse panel. No need for a fuse or the resistor. Kent's 4 position descriptions now makes sense but I'm still seeing a 5th position on my switch past the 4th headlight position. seems to duplicate the 3rd parking light position.