Fuel gauge woes

[alderan33]

I have a recently purchased 72 c10 and I’m trying to get the fuel gauge working. I have replaced the sending unit and gauge and tested both outside the truck. I have tested the sending unit wire from the tank to fuse box for continuity. I have tested the printed circuit board for signal. All good. The gauge reads 3 o’clock indicating no ground from what I’ve read. There are two gray wires labeled cluster coming out of the fuse block. One has a female end that isn’t connected to anything. The other goes up under the dash. The wire cluster going into the back of the gauges looks good. Any help would be immensely appreciated.