It was a hard decision to get an OEM coil or a aftermarket coil since the price difference was significant. As i read user reviews of the aftermarket coils, I noticed repeated laments of early failures and poor fitment. Since the coil uses a capacitor discharge circuit, I surmised that the aftermarket part are using a lower voltage rated capacitor. The part I received from Jack's had OEM part marking and packaging. It fit correctly and has been functioning for several hours at this early date. I hope that I am through the " Infant Mortality" stage. Now, I am hopeful the long term reliability will be satisfactory.