If the Dodge ballast has 4 terminals, it's got two resistors in it. One is somewhat higher resistance than the other. Use whichever side applies about 9 volts to the coil during normal running. If you're planning to use the 6 volt coil on 12 volts, it might be possible to run the two resistors in series to drop the voltage enough to make the coil safe to use.
Jerry


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