2000 mustang wiring problem

[carpenn]

I'm trying to hook up my new system, and i ran into a problem with the harness i was sold. It supoprted the power/dimmer/ground/etc connector just fine, but there is also 2 other connections that went onto the factory deck that are not supported on the second connector given in the aftermarket hardness adapter. So, i dedided to chop off the connector that ran to the speakers in the car, low and behold there are 8 wires, all different colors and not matching or labeled at all inside the larger cable. How am i supposed to tell which is which? I have no clue how to tell which is the positive and negative for each speaker. Any insight would be immensely appreciated, thanks!