Differences between the Pertronix coils is one has internal ballast resistor, and one does not. I've used both Pertronix and the Mopar one (which is what Summit is based on). Both gave me zero problems. The one advantage the Summit kit may have is if the distributor is based on the Mallory design, is you get a fully adjustable mechanical advance. Bad news is MSD bought Malllory out and wasn't allowing that distro to be repopped. But that was years ago and they may be doing it now.