OK.... Has the old cluster gauge worked before? If yes.....I hooked up my VHX fuel gauge input to the ONE signal wire from the tank, and the ground to the dash frame.
You don't need a separate ground wire from the cluster box to the tank sender. The tank sender should have the old ground already hooked up back in the trunk by the filler neck.
VHX uses an interface box that you directly connect those wires from your big cluster plug into, The fuel gauge has 2 connections at that box.
One for the signal wire.......the one from the cluster plug.
The other from the ground.....any ground.
The VHX comes already set up at default to work with the correct ohms of our STOCK GM FUEL SENDER. However, if someone installed some Bastard Fuel Sender with another ohm range other than the GM, you can change this, it's easy.