I would replace all of the water hoses. If you have been consistant with oil changes then your timing chain is probably good to go awhile longer. Make sure you keep the radiator coolant clean/changed. The window regulators will eventually go out on (based on how much they are used) you but they will die a slow death. Changed the rear differential fluid lately?
I have found that anything that is rubber needs replacing on mine.
'85 300D 219k miles