Wiring diagram. I have a 2004 gmc pick up. I want to hook up an auxillary amplifier to my existing

Question

I have a 2004 gmc pick up. I want to hook up an auxillary amplifier to my existing stereo.I have a converter to change stereo outputs to rca outputs.I need to know what wires and colors I need to hook up to the converter.It has the Bose system in it.Any help would be appreciated. The dephi part number is 12246889 the gm part number is 10357886