I never owned a Mercedes stick shift car but on other cars and my motorcycles the proper clutch adjustment was critical for to get the vehicle into gear without a struggle. My 5.0 would go into first easily but reverse was a pain when the clutch needed adjustment.

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1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T