Matt, this is what you want:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1Y70MFKNH1YM0LS2RF&year=1983&make=MB&model=300-DT-001&category=F&part=Voltage+Regulator

AS you can see it's only held in by 2 screws. Super easy to replace.

There are diodes and such in the alternator which cannot be replaced. If they go bad it replacement time.
Sd blue just wrote a testing procedure a few posts back.

Danny

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1984 300SD Turbo Diesel 150,000 miles

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