So here's the story, just for clarification:

I'm from the US, moved over to Germany, and now have a C200 Kompressor.

The car came with a audio 10 tape deck and no changer. Needless to say, that will not suit the needs today. I brought an Alpine headunit over from the US that I had for many years and is in excellent working condition, and has an aux input, as well as a cd player. Its vintage is about 2001/2002. Actually, about a year and a half ago, the original crapped out, and I got this ebay replacement, NOS for $50, so it's just about new. I'm not afraid to solder, but I'd rather do it in a harness than in the factory's wiring, in this particular case. My previous car was soldered and held up for seven years.

Now my goal is to find a harness, wiring diagram of the car's plugs, antenna adapter, and a DIN faceplate. I've already pulled the dash and the original radio out to see what I'm up against and the dimensions.

What is a good source? The reason I also ask on an English speaking board is because my German still isn't good enough to pass a technical level conversation.