ext I'd pull ALL the rubber off the car, and replace it. Check all door seals and trunk seal. Not window seals yet.

front to back, all the steering joints, shocks, bushings, bearings, subframe mounts, etc. Check
everything.
then get a nice color sanding and clear coat paint refresh. This is going to take dynamite and earthmoving equipment.
brakes flushed, and all components updated. Check. Do that every two years religiously. Same with tranny/diff fluids.
steam clean the interior, and replace any seat springs or install the foam inserts to improve the seat comfort. Steam check. Foam inserts ala gsxr/Dave Check. Also recovered front seats with the good Benz Tex stuff.
All windows work. Ant works. Hell even the A/C works although converted to the bad stuff. New windshield. Real Euro lights.

If only the MB dealer wanted an example of why a MB is a long term proposition and would cover the paint job, I would drive around as a billboard.

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87 300D 265Kmi
Factory rebuilt crate 603.96x engine at 200K