First time posting here on CF. I am trying to get my 68 Camaro back on the road and get the fuel gauge hooked up properly (it never did work). I ordered a new sending unit, the sending unit wiring harness,and an OEM block resistor from heartbeat city. The existing set up had none of the wiring going from the harness to the tank. What I need to figure out is the wiring that goes to the back of the gauge it's self. There are 3 studs on the back of the fuel gauge but nothing there. Can anyone shed some light on what I need to do for proper hookup/function of the gauge.

 

This schematic may help.
Tan wire from gauge to sender.
Sender to ground, the pass side trunk support.
Gauge has accessory power and ground to it.