I learned that the brittle plastic cap that started cracking and chipping when I tried to remove it is an access to test the rack movement. I removed the cap, and here are my measurements with my bolt:
- resting: 32 mm from housing
- pull out: 34 mm from housing
- move throttle linkage to max: 34 mm from housing.
- push in: 15 mm from housing.

So it moves 2 mm out from resting, and in 17 mm from resting.

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Past mb: '73 450sl, '81 280slc stick, '71 250, '72 250c, '70 250c, '79 280sl, '73 450sl, parted: '75 240d stick, '69 280s, '73 450slc, '72 450sl,