It looks like that's just one part of the connector - the outside. There's also an inside part, which appears to screw into the outer cap. I think the number on it is 0085452028, but the numbers are tiny, and I can't find my 10x loupe. A search for that number on Pelican Parts turned up:

Pin Bushing Housing (but no pic; can't confirm).
Part #: 008-545-20-28-MBZ $3.75

Since it is described as a housing, I wonder if you might also need:
0035452626 Electrical Pin Bushing.

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Marshall Welch
Seattle, WA
1982 300D-T