Update:
After hours of testing and diagnosis, I found that BOTH my 12v reproduction fuel gauges are working.
Apparently, a quick touch of 12v power to the sender post on the gauge did not kill it.
So, what was my problem????
I changed the wire from the ignition switch to the fuel gauge. It was my last resort.
I replaced the 18ga wire with 12ga. That's it. Nothing more complicated.
After ordering gauges, removing the cluster, replacing gauges, checking the sender, grounding the sender to the chassis vs the cab, lying upside down for hours, it was all for nothing. I even tested the wire that I replaced for continuity.
It's beyond explanation.
