I purchased a Pertronix Ignitor point conversion kit for my distributor. The instructions indicate that I must purchase and install resistors in the 12v lead going to the kit if I have shift interrupter. I don't know if they are referring to an ESA switch. Is the ESA the same thing? How would I know if I have one? Every reference to and ESA switch indicates that it is installed on the throttle linkage. I see nothing.