I have a unit removed from a '93 525it. Mine had a pioneer head unit. I'm
not positive, but I think that some of the head units were made by Alpine,
and the CD changers aren't interchangeable between the two.
Mine has two connectors, a din plug with 14 pins and a power connector in
white nylon or plastic with two connectors. It is flat on the bottom, and
has a sort of gable shape at the top.
If you are interested, and want to check it out for correct function, I can
provide all of the model and serial numbers off the back, even digi-photos
of the unit and connectors. I'll also provide full history on why the unit
was removed and saved - long story.
Let me know. Don't hit reply, type in the email below with the "at" and
"dots" replaced correctly.