Sounds like quite the 'Frankenstein' car. There are numerous fuel system (and other systems) parts that changed over the years, particularly the big change between the 84 and mid 85 cars. I would strongly suggest that you sign up for the free version of the EPC over at the Mercedes web site, so that you can check what the current part compatibility is, and consult with the W201 experts over at 190REV.NET , if you haven't already