Welcome to Peachparts! For springs, you can check out the used parts section and put a request up if you don't find what your are looking for; otherwise, PelicanParts carries them. Check them out here:

1984 Mercedes-Benz 300D Base Sedan - Suspension, Shocks & Springs - Page 1

I can vouch for the quality of Lesjöfors; have no experience with Bilstein but their shock absorbers are second to none for a factory ride.

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[GONE] - 1995 Mercedes E300 Diesel - 130k miles - Smoke Silver (702) over Mushroom leather (265) - Bladder blasting, coast-to-coast work machine.