I pulled a pair of rotors off an '83 300SD yesterday, and the only problem I had was the control arm was too low, pulling on the park brake cable, applying the brake.
Where was this set screw supposed to be?...between a couple of the lug holes on the surface the rim mounts?
Richard

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'83 300 TD..."Helga" Norse for holy... a liittle rust problem
'85 300 TD...A $200 rear-ended total..being transformed into a pick-up truck
'68 Ford Ranchero GT...a pick-up truck that Ford transformed from their wagon