After doing the "battery pop" test I have written down the stereo wire colors from the factory harness.

Right Front white/black -
Right Front grey/black +
Left Front white/red -
Left Front grey/red +
Right Rear white -
Right Rear grey +
Left Rear white/purple -
Left Rear grey/white +

I didn't test the other wires to figure out power, etc. This is for the 4 speaker standard stereo.