The problem is the interface on the head units we have. The NAV has a mono input that is the old-style mobile phone input and a mute line. When you ground the mute line, the radio mutes and puts any audio on the mono input out thru the car's speakers - on one side only (passenger side if I recall right). I used this input for my FRS radio when running the Dragon when I had a NAV head.

It is not suitable for music at all. And that is the only input I see, other than the digital input from the CD Changer that Rudy used for his mod.

I don't know if Rudy checks in here much anymore... maybe he will chime in.