Does anyone has a stereo wiring diagram for '84 300D Turbo? Any help would be helpfull.

i dont have a wiring diagram that is stereo specific what questions do you have?

On Mercedes original Tape player I have power plug with 4 prongs, marked 1-4, power antena plug, and speakers. On my new stereo I only have 3 power wires, plus power antena and speakers. The question I have is: where do I wire my 3 power cables from the new stereo to the original 4 prong conection on mercedes?

I've found conector diagram on becker site.
1- ground (brown)
2- ignition (black)
3- illumination (gray)
4- constant (red)

if you havent by-passed the fader in the center console, youre only going to get %50 power output to your speakers...which could blow them. Whenever you put in an aftermarket head unit you need to wire the speakers directly into the head unit (unless youre running an amp).

Here's the connector for alot, if not most, of Becker's Grand Prix radios. http://home.comcast.net/~aszablowski/beckerconnector.jpg

As for the speakers, do it right and run your own wiring to them from the head unit, bypassing the fader in the center console.