4 pin and your parts house will have a basic Mopar standard motor products one in either 4 or 5 pin which is pretty reliable but if not whatever they have is fine. The ECU is pretty much just a switch for the pri current like the points used to b and an ECU can handle switching quite a bit of current so if you toss the ballast & get a full 12V coil as it's the ballast/coil combo that must match (for longevity) and which is what decides the amt/duration of the spark energy.