Up through 1969 (with a couple exceptions):
Ignition 1 (run) should be power to the voltage regulator. Regulator out to Field terminal. Circuit completes to ground at second field terminal.
1970 up.
Ignition 1 (run) goes to both the Voltage regulator and one of the Field terminals.
Circuit completes to ground by connecting the second field terminal to the regulator. This type of regulator measures the voltage on the Ign 1 wire, but controls the power by switching the ground wire on/off.