Welp, replacing the left-side tie rod fixed most of the problem, but in true Mercedes fashion, repairing one problem exposed another, smaller one.
It seems my idler arm bushings are shot, as I have a slight (<1 degree) random steering wiggle that only manifests with the wheel dead center. While I was under the car, I noticed the control arm bushings look pretty crappy too, so those may be contributing to the problem.
Onward!

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RIP:
2011 E350 BlueTEC, Schwartz 81k (totaled by uninsured drunk driver)
1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)