Not sure on the wire colors, but when I bought and installed my retro sound, a jumper harness was available that plugged right into the factory radio harness connector, and connects to the new radio with instructions. I remember it being very simple. Based on their catalog now, 70-1677-1 is the part number I used. Hope this helps
I don't know how many times I've had to fix other peoples botched stereo installs when they would cut the factory harness out of late model cars that all had adapters available. If there is a harness adapter available they are worth the cost.
If theres no factory harness connecter or if someone has clipped it off you've got some work to do, label wires with each step:
With the key off test each wire with test light for the battery +
With the key on acc. test each wire for the ign. hot wire
Take a 9 volt battery hold one terminal of the battery on a wire then tap each other wire on the other terminal until you hear a speaker make noise. Do this until you have a pair for each speaker.
last wire left should be the ground, if no wire is left the ground was through the chassis of the radio to the dash or through a bolt supporting the radio in the rear.
if more than one wire is left:
There could be a wire to dim the screen/lights when the headlights are on. More common in late model cars. There also could be wires to turn on an amplifier or motorized antenna if equipped or available as an option from factory..
figure out the polarity for the speaker wire pars: watch the speaker while you connect the 9V battery, if the cone moves out then the way they are hooked to the 9V battery is correct. Positive wire on the + battery terminal. If not switch the wires and test again to be sure.