For the USA market, VW switched to 12v with the 1967 model year.
Chances are high it’s a 12 volt, negative ground.
This sounds obvious, but you say there is a battery; is it in the car? Is there a ground strap on the battery? Which pole?
Looks at the bulbs. If they are 12v bulbs, you have a 12 volt, negative ground system.
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
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