HELP 76 dart gas an temp gauges wont work!!!

1976 cars should have an electronic voltage regulator. It is a thin, square box with a special triangular connector with 2 pins. If missing the connector, a junkyard is the best source for both, though I think you can buy new connectors still. A new Vreg is ~$12 at most parts stores.

turns out the in dash regulator around here is 37 at auto zone and 54 at napa. it took them a while to find it cause they kept pulling up the one under the hood.