Sorry to go over this again, but i'm a bit confused. I've done quite a bit of searching and it seems like there are two harnesses that most people are recommending. Is the Metra 70-5511 the correct harness for a 2000 GT with mach 460 when installing an aftermarket head unit and using the stock amps/speakers? What about the 70-5510? And the 70-5519 is for the 01+ cars right? Is that the only harness that is needed?