She most likely has the two channel speaker layout as in all older
Mercedes... where you have a separate fader control on center console.

What you need to do is disconnect that fader and find out which wire of the
harness goes to which speaker... and then splice it into Kenwood. unit.

As for power... you have to use multimeter to determine which is which...
brown is ground (black) and blue is antennae... still blue. There is
probably a grey wire... and that one is for light which will correspond to
orange I think for night dimming.