Is it a big cap HEI distributor?
If so, the one wire (or just a empty spade connector) coming from the terminal marked btty goes to ignition hot. I believe that to be black with a yellow stripe near the factory coil location on the right inner fender. The terminal next to it marked "tach" goes to a tachometer if you want to hook one up. The 3 wire connector that goes from the cap to the distributor is the wires from the pick up and module to the coil.
If it is a small cap with one wire coming out of the distributor it is a points distributor and should be thrown in the bushes and replaced with an HEI. That one wire goes to the negative side of the coil with ignition switched battery voltage to the positive side of the coil. Really HEI is cheap and simple and works loads better than crappy old points. It sounds to me like this is what you're seeing.
If it is a small cap with two weatherpak connectors, one four wire, one two you have a computer controlled fuel injection distributor that requires a computer to advance the timing. The two wire connector goes to the coil, the four wire to the ECM.
