u/Zestyclose_Long_6787

I have decided to buy a 1989 300E with roughly 200,000km on the odometer, I was always fascinated by this car and decided to pull the trigger, what are some of the common problems that I should look out for or ask the owner if the repair/replacement has been done? I have heard about biodegradable wire harness and vacuum leak problems, are they as common as they say?