I believe you are looking at the ignition switch pigtails. The factory tach harness has two separate leads that plug directly into the the bullet connector leads coming off the tach. The tach is part of a series circuit that does connect to the pink resistor wire in the harness. And yes if the tach fails, you have no spark, hence why some people have them re-wired to be on a separate circuit. If you are replacing the ignition switch pigtail, the one with the pink wire is correct.