I'm pretty sure those are M12x1.75mm. 80mm long with unthreaded shank, I think the thread is 30mm long?

My car had two hex socket bolts, which I replaced with Grade 8.8 hex head bolts. Now I can remove the starter from above, without needing to take out the engine to clear the sound insulation.

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1995 W202 C250 Diesel, OM605 NA engine, 5-speed manual
1986 W123 200, OM617 NA engine, 5-speed manual, rev counter
1989 W126 300SE, 5-speed manual