right
there are a lot of pieces at play
12V coils with internal ballast resistor
12V coil without resistor
6V coil
old timey first generation 12V batteries that had so much internal impedance that the crank voltage dropped ridiculously
my truck is using a 6V coil, and the external resistor is meant to drop the voltage by half so from the ignitions point of view it is running on 6V still as original
there are a few ways to do it, what every shop or farmer did my truck was just the flavor of the week
-s
