fuel cell wiring, need some help.

OK, now which wire goes where? positive, negative, and signal to guage?
This is my fuel cell with a GM style sending unit.

one is a bolt (biggest in center), one is a screw (top), and the 3rd on the bottom is a male spade adapter.

I am assuming the bolt is the hot wire from battery, the screw is ground, and the spade is the signal wire. Is this right?

are there any markings on the plate? i can't read it it's blurry