Christopher,
Many of the three brush generators can be run just fine by replacing the cutout with a voltage regulator. Additionally, on many three brush generators, the output of the generator can be adjusted by moving the third brush. The third brush is mounted on a slide for this purpose. The point of this was to set the generator output for the type of driving you did. For a lot of stop and go, the generator would be set to high output to keep the battery charged. If you did a lot of daytime long distance driving, the current output would be set low so as to not over charge the battery.
The cutout does not control the amount of current the generator produces, whereby a voltage regulator will. So to use the generator with a voltage regulator, the third brush can be moved to produce max current and the regulator will control the output.
Main thing is if you want to move the brush all the way over you will want to know what the max safe amperage the generator can produce so you can match it up with the right voltage regulator. Or just keep the brush where it is and use a standard 6v regulator.
I'm a fan of keeping all the original equipment you can. So even if you replace the genny and cutout, don't toss it. The next owner may really appreciate having it.
Kurt
