Instrument cluster voltage regulator, on a 1970 Plymouth Valiant, 340 Duster

No, only the amp gauge is not associated with the limiter. The other three are. The fuel gauge has a 3rd post which is the 5V output and feeds to the oil/ temp gauges. See Red's post above^^

In fact you can see it in the photo posted, marked 5V

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If you thrash around the www there is a procedure to feed an external 5V regulator or IVR into the fuel gauge 5V stud and do away with the internal / OEM one