Need Gauge Wiring help!!
 

Okay, I need some help from the experts.I bought a new Gaffrig Fuel gauge. It is different than my old gaffrig fuel gauge. I have a pink wire, a purple wire, and two black wires one of which is thicker than the other. I know where the pink and purple wires go do to the gauge being labeled I,S and G. The old gauge does not have a G labeled but does have a post where it is labeled on the new one. The old gauge has a plastic piece on the back of it with metal running through it. (To power the light I assume) The new gauge has the I,S,G posts and 2 small posts on either side of the light bulb housing (No Plastic Piece). My question is where do the thick and thin black wires go on the new gauge? It's a 97 Fountain if it makes a difference.

G Ground both black wires there

If I do that what will power the light?

Is there 2 black wires on the light or a black and a white?

Both Black. One thicker than the other. No white wires at all.

The metal piece on the old gauge was the ground for the light.Like stated earlier, the g is the ground for the gauge, S is sender wire from fuel tank, I is the ignition wire. Because of the two terminals on the light you will have to run a ground to it unlike your old gage. This can be jumpered from the G terminal. Use a test light and switch your dash lts on and off to determine which is the power for the light.Usually blue, but could also be black.
Steve