I told a battery installer it was a $100.00 secret. We got a '60 Caddie in and had put 4 batteries in it. I touched the wire, good to go. Then I pulled the owner aside and told him how. That caddie was a great story.
Here's an old post attempting to sort out the two different and non-interchangeable ways of polarizing common 1950's-1960's cars. Write down the one you need and save that! Asking, especially on the internet, is dangerous to your regulator because 50% of the replies will insist that their chosen way is correct. https://www.jalopyjournal.com/forum/threads/flashing-the-generator.256038/ This other post is an attempt to organize a bunch of fairly simple generator tests http://www.jalopyjournal.com/forum/showthread.php?t=278956&highlight=generator+polarize&showall=1