Be careful. The + never goes to the fuel tank. It may spark and explode. My guess is that the fuel gauge us for dual voltage. Verify before going further.
I ordered a new fuel gauge from Kaiser Willys, but the new gauge has three terminals instead of the original two. The terminals are marked, +,- and S. I'm assuming + goes to the ignition, - to ground, and S to the sending unit. Am I correct? The wiring diagrams I have are for a two terminal gauge.