If your 83 300sd is like my 90 420sel, you would be better off just unplugging the becker and leave the factory plug behind the dash, in cas you ever want to plug the becker back up. I would then, rewire the stereo to bypass the amps because with an aftermarket deck, you may pick up a whine in the radio. It is a very easy job to rewire it and would be very easy to go back to original settings if needed. You will lose the fader on the console, but you will have that on the deck so you won't need it. When you get done, the sound from your aftermarket deck will be awesome compared to the old becker. Email me if you want further instructions on how to do it and the supplies you will need. My email is scottfish@peoplepc.com . I rewired my 420 and helped rewire my wife's 300 se(first one done).