Correct me if im wrong, but my understanding is that there is two different types of HEI that were put in our trucks correct? One with 4-prong ignition module and one with 5-prong ignition module (Electronic Spark Control). Are these basically the same except the system with the 4-prong module doesn't have an extra connector with wires running to a little "computer"? or am I way off base. Next question: if my blazer has the Electronic spark control, can I switch it out to the other distributor? I really wanna figure out my ignition problem and the only thing really left is that electronic spark control. The whole distributor was new and the distributor wires are all good and it still doesn't get spark SOMETIMES. It has to be either that or the ignition switch, but would it cause this intermittent problem, and where is it at? I am in desperate need of help!!!