Thanks.

I went into the Dealer and had them do a parts search, to see if the receiving unit was used on any others Toys, or if the parts numbers cross referenced with any other receiving units for the coolant or volts gauge, and nothing turned up. The units are basically the same, no ID numbers on either one, and the brass caps both have an "F" on the back.(Left is the volts, Right is fuel)


At any it seems I have fixed it for now.
After messing around with it yesterday, I determined that it was an issue with the ground circuit on the cluster itself. With the Fuel and Ignition screws in and tight, I would get the correct readings between all three as long as I left the Engine(-) screw out(with it in all the readings fell way off). I decided to isolate the ground and ground the receiving unit to the vehicle.

When I plugged the cluster in, the fuel gauge was above the "Empty" line, and fell down to empty with the key on. I put 4 gals in and the gauge rose to 1/2, which is about right, there was about 3 gallons in it and it is a 13.5gal tank. Just to make sure it was the ground, I removed the ground wire and returned it to oem set-up, and the gauge remained at empty. I will fill it up later this week and see if the gauge moves to full.

I ordered a complete cluster which arrived yesterday. I went ahead and tested it and it tested bad, same as the original. Thinking it was me I installed it, and same issue. I reinstalled it after adding gas, and it still read "Empty". I isolated the ground, and now it works. I am not sure if it was just bad luck to get a new used cluster that had the same issue, or it is the truck.