Skip is right:
I went out and carefully checked the TD and there is a rubber
ring. The rubber is not a seal or boot, but a ring used to
supply pressure against the metal cups that act as grease seals.
Both the shop manual and the factory parts book refer to these
rubber pieces as a "pressure ring-for caps." They do not enclose
the metal cups which are always visible and that lead to my
error. I always remembered that the metal cups were visible
whenever I greased the tie rod ends, and that's because the
rubber doesn't enclose them.
You probably could manufacture something similar to this from
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