Usually black is ground, and red is positive, so that is why the question is being asked. If this is just a representative photo from the web sight your ordering from, then who knows what is what. Now to answer your question, the fusible link is a separate wire, and where the alternator wire ties into. Reason being, if the alternator fails in wide open charge mode, it can blow up the battery, fry the wiring going to the battery ECT. I had this happen on my truck several years ago. Before it burnt the fusible link, it burnt through the aluminum coolant line just behind the alternator, burning a hole through it. I ahd to replace it when I replaced the alternator, and had to get a new fusible link because it fried too.