No one has spoken specifically on the 300SD that I can remember. There was a thread on W123 Boots a month ago that had the number of a split boot for W123s that a few have used. I am at the library and don't have access to my notes.
Search diesel discussion for Productive Input On Split CV-Boots? that is the title of the thread.

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84 300D, 82 Volvo 244Gl Diesel