New voltage limiter questions - 67 Dart 270

Hey there,
Welcome to the forum. I have a bit of experience in this realm as I myself am in the middle of making some upgrades to my instrument cluster.

I don't think adding a ground to the extra prong. It might be a good idea, but probably not critical.

I'm not sure about the wire that glued wired might be for, but that's probably something you would want to put a connector on and affix properly. Because whatever adhesive you choose will probably wear out over time.

Regarding the limiter itself, I recommend that you test it before putting everything back together. I just bought one (Airtex brand) and it didn't work properly. When it was hood ked up the gauge was bouncing all over the place. Put the voltmeter on it and it wouldn't really register. It would bounce around so much that nothi nothi registered. But I know some power is going through the limiter because the gauge would move. Apparently those new solid state limiters are supposed to bounce the voltage around to mimic the action of the old mechanical limiters, but mine
was doing it all wrong. So I bought a new one from a supplier up here in Canada (National Moparts) and the new one works perfectly.