When my 300SD's linkage fell apart, I repaired mine by drilling and tapping a hole in the top of the ball, and a matching hole slightly oversize drilled in the socket.

With a good bit of good grease packed in the socket, it was put back on the ball and secured with a washer and a capscrew, along with a little blue Locktite.

If you're going to do this, it helps to have access to a drill press, as the ball is a pain to get to stay still, and may also be hardened steel.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...