I have a 1983 240d and i wanted to add a tach. so i looked around at some guides and im stuck. i got some parts off a 1985 300d turbo, like the sensor at the crank and the black round thing with the cap and the tach, but i dont understand where to hook the cables.

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1974 240d
1983 240d -sold
1989 420sel with om606
1994 s350 turbodiesel - sold