Attached pics are the repo gages that I put in my '69 back in 1994. Just had them out a couple of weekends ago to change the resistor on the back of the temp gage - which is when I took these pictures.
Looking at the cluster from the bottom, the fuel gage has two connections (bottom right in the first picture).
Temp gage (top left in the 1st picture) also has two connectors. but the bottom lug (cal resistor) of the temp gage needs to be connected to ground. That is the separate gray wire that is in the first picture. That gray wire and a ground lead from the wiring harness is connected to the hole in the mounting plate. This is the main ground for the cluster.
The second picture is looking down on the gages from the top. I've put this in to show how I grounded the front mounting plate (for the fuel and oil pressure gages) to the rear mounting plate where the main ground is connected. That is the 18 ga white wire that you see connecting between the front and rrear mounting plates.
The repro wiring harness that I ordered also had the low fuel warning lead - I did not use it. You do not have to connect it to have the gages functional.
Both the fuel and temp gages (original style) have external calibration resistors that have to be working properly. I believe the new OER repo gages now have these resistors built internal. You also have to be sure that the lugs on the back of the gages are properly iisolated.
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