Stereo wiring

Truck did not come with factory radio or speaker wiring. I want to connect new radio to existing radio wiring harness, which includes speaker wires running to unknown location. I need to know the location where the radio wiring harness connects to so I can connect my new speaker wires to the same junction box, just like it would have been done at the factory.

I have the aftermarket wiring harness from the radio to the factory harness. But where do I connect the speaker wires coming from the speakers? Do I have to splice into the harness wires? There are four pairs of speaker connection wires as part of the factory harness running to some location/connection board somewhere - that is where I should connect the speaker wires that I installed, just like it would have been done at the factory. Where is that location/connection board? Thank you for helping.

I installed speakers and ran wires from the speakers to the radio location. I can splice the speaker wires to the color codes you provided, but I was hoping there is a terminal board or something that the speaker wires would connect to - the same terminal board that the factory wiring harness connects to.

The radio is shorting out from what sounds like a loose wire connection cause I can hear the static thru the speakers. Where do I locate the radio/speaker wire connections?

Thank you for trying to help. The factory plugin harness to the radio connector is there. So the speaker signal comes out of the radio, through the factory harness wires, and then wires from the factory plugin harness go deep into to the dash somewhere, without the option to connect directly to the new speaker wires I installed. The wires that go deep into the dash somewhere includes the four pairs of speaker wires that I need to connect my speaker wires to. If I new where the four pairs of speaker wires terminate, I could connect my speaker wires to them at that point. Otherwise, I have to cut/intercept these wires between the plugin and the unknown location to connect my speaker wires.