Lumina Wiring Harness

Hi , I have a 93 Chevy Lumina . The radio  & factory harness was missing when I bought it . I want to replace it back with a factory equipment . I have a stock radio & I found a harness in the salvage yard . Here is my problem . I don't have a problem with most of the wires , except there are 2 grey , 2 yellow & 2 brown . How do I tell which ones go where ? I hooked everything up & took a 50/50 chance on the grey , yellow & brown . The radio worked , but the fade & balance didn't work right . How do I find out a what the difference is between the colors ?

Thanks!! 

the speaker connections are bundled together, so the grey that is right beside the tan is a speaker wire ( along side the light green and dark green ), the yellow and brown that are right beside the dark blue and light blue are the left rear speaker wires.....

if you got the plug assy with the three separate connectors then its easy because two of the connectors only have 4 wires each and these are all speaker wires... the plug with 6 pins contains the power, ground, dimmer, power ant, etc , etc