Nothing is being "lost" exactly. The simple explanation is, that the second resistor in the 4 pin ballast feeds power to part of the box circuitry through that 5th pin. The 4 pin boxes were re-designed circuits and did not need that. Here, by the way, is the simple diagram of a GM 4 pin
[URL]https://www.forabodiesonly.com/mopar/attachments/4pin-jpg.1715082093/[/URL]
If you use one, pay attention to the distributor pickup "polarity" as it will offset the spark event in relation to the rotor (rotor phasing. The GM modules have a locating "tit" which you either must drill for clearance in the heat sink or just cut it off. Make sure the module is mounted flat for heat transfer, and grounded. The mounting screws are the ground.
Also bypass your resistor. Many on here argue., but as an experiment, I used my stock coil and "it lived" just fine, and provides a better visible spark than Mopar. I also did not use a heat sink for same reason, "experiment" I simply mounted it to a flat area on the firewall and there was already a mysterious sheet metal screw there handy for one mounting.
Do NOT try and run the GM module without being mounted to some sort of heat dissapation/ sink.
