On my '64 Tempest I ran into the same problem while installing Sylvania Halogens. I removed the 3 brass push-on connectors from the plastic boot by carefully pushing the retaining prong on the connector inward with a thin small jewelers screwdriver, saving the plastic boot from destruction. I then used shrink tubing to cover the 3 brass connectors individually and pushed them into place on the new headlights.
Pissed me off to have to screw around like that just to install some new headlights.
Let's go racing!
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