Indeed, '84 and '85 still have the front pickup for the diagnostic socket (formerly location of tach amp) and the tach sensor was moved to the rear. Same on the W126's.

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'17 Metris(VITO!) - 37k - wifes (OC-41k)
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'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
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