Guys: I did try the system with the new regulator - unfortunately, it still stalls when the positive battery cable is unhooked.

You are right about one end of the brown wire going to the ignition. Having said that, should that be hooked up, or should I disconnect it? I'm assuming I would disconnect it, as that function (lighting the gen light when the key is on) is no longer needed with the rally gauges. However, maybe the regulator won't work unless this brown wire has power.

Thanks for the info on testing the regulator for ground. Who knows, maybe that could be it.

By the way, the brown wire has a diode soldered to it at the female spade connector. What is this for? Is it needed?