65 dart Fuel gage

If the gas and and possibly the temp gauges are inop, the instrument voltage regulator which regulates voltage (5 volts) to the gas and temp gauges is most likely the culprit. In the 65 Dart it is a combination unit combined with the gas gauge and once the gauge is fried, it's gotta be replaced. I've got several loose ones as well as a complete operational instrument cluster from my 99,000 mile GT convert (I have a NOS instrument cluster/bezel going back in when I get to that point). If you want one of my loose fuel gauges (no guarantees on working since I don't know the history on them) you're welcome to one. PM me your address and I'll send you one.