Mercedes: Buying a used 200-series Diesel, mercedes diesel, series diesel

Question
I am interested in a used Mercedes diesel(1980-1985)but I know little about what to look for or what to ask the sellers. Are there better years for MPG or known defects in specific years. How many miles is too many miles? Thanks for any help!  

Answer
I suggest you join:

Diesel Discussion
http://www.mercedesshop.com/shopforum/forumdisplay.php?f=15

There are many 200 series owners, and none are shy when talking about their cars.
Do NOT buy without a PPI (Pre Purchase Inspection).

Several members have vehicles for sale.

Cars
http://www.mercedesshop.com/shopforum/forumdisplay.php?f=24