Technical 26 roadster fuel sending unit????

I have an aluminum fuel tank.. there is a stewart warner sending unit in there.. on top is a plastic fitting that has 2 pins in it....im guessing one might be for a ground...and the other to the gauge... any ideas??? when I took apart one wire goes to the bottom on the unit where float is the other is soldiered to the top spade of the plastic ***embly .. hmm .. any ideas

 

Most times the center pin is the gauge sender wire. It works off the reostate.

 

The post that has the wire to the rheostat/float arm is the one for your gauge. If the other is soldered to the frame then it is a ground connection. Most senders gain casual ground through the tank and mounting hardware, but the additional post provides a solid connection.