I had a 1985 300D...
that I bought off of the original owner. I bought it off of him with 267K miles on it. He was a salesman that used it to travel around so I knew that it was driven hard and long (diesels love this, I'm told). He took it to the dealer for regular service so I knew it was taken care of.
I had it for almost 2 years before I sold it to someone else.
When I bought it off of him I went to the dealer and they let me go thru the service records (they would not let me leave with them however). It had the original engine and trans and it ran great. I kinda' was bummed to get rid of it but the Michigan winters and salt had taken it's toll on the body.
Anyways, if you can get ahold of the cars records and history you should be okay.
84 500SEL EURO 101K ( JUST LIKE MY 1ST WIFE. GLAD TO GET RID OF HER! )
85 300D 310K (sold)
90 350SDL 184K sold
83 300D 118K (sold)
88 300E 153k (sold)
93 400E 105K (sold)