Quote Originally Posted by knightrider View Post
So just to be clear that universal 558-307 harness needs to be pinned into my main harness I have now?
No, it's much easier than that. Your main harness remains "as is". The Holley 558-307 CNP main harness has terminals attached on the nine loose wires for connecting into the J1B ECU connector. Here's the instructions (LINK).
https://forums.holley.com/showthread...-For-CNP-Coils (Related Forum Thread)