You're describing a 3-brush generator with a cutout relay and resistors mounted to the headlight switch to increase generator output while using the headlights. The cutout relay keeps the battery from discharging itself through the generator when the engine stops. I've got some Delco-Remy technical bulletins covering that system that I can scan and copy if you're interested in keeping it original. For simplicity of operation and reliability, I'd suggest swapping to a later model 2-brush generator with a 3-unit regulator, but staying with the 6 Volt electrical system. The only reason to stay with the original system is if you're doing a totally original restoration. The old 3-brush generators did a really lousy job of keeping the battery charged. It's easy to adapt the system to a slightly more modern setup.
Jerry

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