HEI Extra pigtail?
 

I recently picked up this HEI for my 72 350 but it has an extra wire pigtail shown in picture on left side. Can I use this HEI on our trucks and if so what is done with the extra wires (IE what do they do or what won't they do if not hooked up)?

looks like the ESC distributor in my 84 Jimmy... Electronic Spark Control... I'm not sure if it is necessary or not.

Yep its for ESC and without the ESC module connected, the ignition will not fire. You can replace the ignition module with a regular 4 pin and just remove the ESC wiring.

You can also jumper 2 of the wires to bypass the ESC control but I dont remember which ones right off hand. I can look into it if you need me to.

Ok I tried switching the modules but that doesn't appear to work as the new 4 pin module has only 2 pins going to the esc area (1 large 1 small) and the original ESC module has 3 pins (all small) so they don't go into socket. Tried removing the whole pigtail (socket and wires ) for ESC but the other end goes down into the distributer housing and is mounted to clip or ring inside there.(RED ARROW) I dont think I can just pull wires out. Any Suggestions? I surely can't be the only one who has made this mistake of getting to new of a distributer. thanks again