Looks like the Mercedes-branded version of the Becker CDR 220, found here:
http://www.swstereo.com/Products/Becker/becker_recs.htm

I spoke with Stefan of SWSTEREO and he recommends the CDR 210 because the W124's stereo location makes it hard to read the display of the CDR 220.

You may want to consider the "gray-market" Beckers, not officially imported to USA.

I would consider the Becker Mexico CD 4337 (7803 with blue backlight), or if you want a subwoofer out, it would be the Becker Mexico Pro CD 4627 (4625 with blue backlight).

Check them out here:
http://www.soundlabsgroup.com.au/Becker/Becker_Range.htm

Need to know the Becker wiring diagram for all Mercedes Benz radios from 1994 to 1997 that have the DIN-ISO connector, check here:
http://www.beckerelectronics.com/1492.html
http://www.beckerelectronics.com/connect.jpg

Some technical & error code info:
http://www.beckerelectronics.com/stereo.htm

:-) neil
1988 360TE AMG
1993 500E