I am about to start upgrading my audio system as well. I also have a 1982 300D-Turbodiesel. I had a sales person at a good local car audio shop look at the car and he measured the stock front speakers and told me that they were 3 (three) inches in diameter. The rear speakers are 4 inches. At least this appears to be the case for my car- maybe other W123's are different.

He recommended replacing them with some Pioneer speakers. He said that the 3-inch size would have to be special ordered.

He said they had done a fair number of upgrades to these cars and that they usually recommended a Nakamichi car stereo (I believe a CD-400) and the Pioneer speakers. This was if the owner didn't want to put in larger speakers, subwoofers, amps and so on. He said the Nakamichi looks good in these cars and doesn't have quite the ultramodern flashy look that young thieves seem to like. It has a detachable face anyhow.

I look forward to hearing more about how your upgrade goes.

-M Welch
Seattle, WA