I just got a 1980 300SD after my 82' 300D was hit and killed. So far i like it alot eventhough it needs a lot of work. My understanding is that between 1978 and 1980 just over 28,000 300SD's were made.
Out to Pasture:
1982 300D KIA (Rice Rocket vs. 123: He hit me at 80-100MPH I walked away he went to the hospital. Sounds fair to me!)
1985 300D EURO Scrapped (got more money from state than car was worth)
1979 & 1980 300SD Great Cars!