Rebuilding my rear suspension this week...

The control arm itself has an inner bushing and an outer bushing.
The inner one is like $8 and the outer one is like $30.

There is no balljoint in that arm.
One of the links, often called a "tie rod" (second from bottom on front) does have a balljoint on it (on the hub end).
If you replace that one, you might consider getting the eccentric bolt kit to go with it.

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1986 300E 5-Speed 240k mi.