New cluster did not fix the dead Gauge issues HELP

Sorry I didn't read all this. Search for my thread on fixing the cluster in my 64 & 65. I tested them on the bench first. Like you, I put an electronic Vreg and tuned the voltage so my gages read perfect w/ test resistors (had to add some shunt resistors to the board to tweak).

I recall that the fuel and temp gages do not require the ground of the cluster. Their sensors complete the circuit to ground. You will not hurt the fuel gage by grounding the sensor input. The needle will peg though. You can get at the wire in the connector under the driver's side kick panel if you don't want to crawl under to the tank. Best guess is you aren't getting 5 VDC out of your electronic Vreg, but a voltmeter would tell you that. It probably isn't bad, and more likely you failed to disable the Vreg inside the fuel gage. Did you read the instructions that came with it? Most Amazon sellers are lax and give no value-added like a clear description or instructions, but you can find them at one ebay vendor's listing (search "voltage limiter" and "Plymouth") or on the RTE site.