I need an isolation module for the NSI dual ignition system on my EA-81. NSI part number was 101-17200-00. Two are used between the 8 wires from the 4 coils (each feed 2 plugs) and the 4 plugs. I'm told the same module was used on the EJ-22 and 25. It's full of diodes which I can't identify. Anybody know how to size diodes to block reverse plug voltage and current?