Chevy 350 2- wire distributor. The black wire goes to the external coil. Where...

...does the red wire go? I have a chevy 350 in a 66 nova. I recently installed a new wiring harness, however, no wiring diagrams show a distributor with two wires (black & red). I believe that the black wire runs to the external coil, however, I'm not sure where the red wire should go?