When got my '84 Euro 300TD three years ago, , I replaced the radiator because it was running hot (95-100C) and there were traces it was starting a tiny leal. The new radiator didn't cure the hot condition, but since then I've checked with one of those infra-red thermometers and it's actualy about 5C lower than what the guage reads.
However, one issue I'd have with an otherwise good original radiator is the hose-necks can snap off the aged plastic tanks without warning. So I'm glad I replaced mine, since the AC still works on this car, and I do take it on occasional trips to Virginia Beach.
Personally, I prefer the old style brass-copper radiators as they aren't subject to 'broken neck' syndrome and they are repairable.

Happy Motoring, Mark

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DrDKW