I just bought a new (used) 89 300 TE wagon. It has the stock Becker Grand Prix cassette radio.

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I found lots O good info about removing the stereo and did that without a hitch. However I am having problems finding info on the stock wiring setup.

I think that this thing has an external amp. Maybe? I found a box marked Becker autoradio under the passenger footwell. It also has fader controls in the center console.

There are 2 plugs, and a plug marked L and one marked R. The power plug I was able to find a pinout for. The other plug is the mystery. It only has 3 wires and an extra bit that goes to a clip mounted to the chassis of the radio. I imagine 1 pin is for the antenna 1 for the amp and the other ?

Anybody done an install into a 'cedes? I don't want to get too involved in this one. I want to use the stock speakers etc...

Any thoughts?