If it isnt one thing its another...

[76GMC1500]

I believe the fuel guage sending unit uses only one wire and a ground. The ground terminal is obvious because it is not insulated. Connect the insulated terminal to the SND (or whatever they call it) terminal on the guage. The gauge should have a input/snd terminal, a +, and a GND. Just wire those up accordingly. There may also be a light on the guage. Bus bars and anything from Blue Sea Systems will make your wiring look professional.