metra speaker wire harness part # 72-5602 it has four wires on it. you have to remove the two middle ones then swap the other two so the neg and pos wires line up with the factory wiring.
Great find, I've only been able to find the harness on eBay or a few other sites but they all want >= $20 for a pair I believe which is a complete rip off. Where did you get yours from?
I found a seller on eBay that sells the Metra 72-5602 harness kits for $6.95 with free shipping it seems. Two kits were ordered (x4 in total) from the seller in which they are also available on their main site for those of you who do not use eBay.
$14 seems like a reasonable price to be able to leave the stock parts modular.