Radio Identification/Installation, Reinstalling the radio in '72 914 Options

[Baumgardner]

When I received my '72 914, the radio was not connected and previous owner indicated they hadn't tried to hook it up. I pulled the radio and sent it in to check out. I was told it was a Blaupunkt “Emden” model and that it worked fine. Here is pic of the radio with some codes which I have NOT been able to identify. At this point, I'm trying to figure out how to properly reconnect this. I was told the brown wire was for speakers, the blue wire was for "illumination", and should connect to dash lights, and the black wire was the power feed. The antennae feed connection is in the rear. I'm a little hesitant about properly wiring this. For one thing, I assume I need to attach a ground from the back of the radio to the chassis? Any advice on this would be greatly appreciated, either in confirming the model or advice on reconnection? Thank you.