They were Positive ground originally.
Positive battery cable to the engine block or head, Negative cable to the starter solenoid.
If it's been disconnected for a long time and you'd like the charging system to possibly work, it shouldn't hurt to Polarize it. If you need instructions for that it's very simple.
With the wiring all connected but before you start the engine, remove the Field wire from the voltage regulator and brush it across the Battery terminal of the voltage regulator, then reconnect the Field wire to it’s position on the voltage regulator.
With any luck the voltage regulator terminals are labeled.
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