38KV

As far as I remember the Gaffrig GSFLC-senders require +12V.
My new senders came today and there's only a "neg" and a "send" terminal.

Is this a new version or what?

Crazyhorse

The terminal on the right labeled "send" is connected to the wire running from the gauge and the "neg" is grounded at the tank. The Gauge is powered from the helm when the key is switched on. The sender completes the circuit by providing a variable resistance (fuel level) and going to ground.

Poorsche

You're right--the previous version required a 12V + input. I just installed one that I've had around for about a year and had to run a wire from sender to dash to get switched 12V.

Poorsche

SSComp

The one shown in the pic is a standard set up for Merc. The values (240/33) are the same too.