Got a free 1990 300ce about 2 years ago and its being abused by me not wanting to spend huge bucks on a replacement ignition module. Is there any other unit that may work? I know the chances are slim to none. Maybe some extreme MB lover went all out and figures out a rewire with a different unit. Maybe MSD???

 

Going through same thing...Put a used M103 module on just to test....car starts and runs but not very well....looking for the same info you are.....
I just hooked up coil and Crank sensor for testing and got big sparks from coil so it is the module that is bad....I am attempting to repair the original module...its a bear to get apart without destroying it but I got it done....If you want to sell your old module just let me know.....I am still analyzing the innards...I just need another one for more measurements.....if you have any luck with other systems ...please post back.....