86 k20 quad headlight wiring question

[vortech71chevy]

Hi guys- converted my 78 k20 frontend to and 86 front end with quad headlights. Uppers are three-prong sylvania’s # 4656. The wiring harness on my truck was cut off a few inches out of the firewall, so i ordered new dorman plugs for the headlights. They showed up today with all three wires being black. Does anybody know which prong is high beam, which is low beam, and which is ground on these 3 prong high/low headlights so i can run the appropriate wires to the correct prong on the back of the headlight? Thanks!
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