MAG58, I don't think that the w124 is that much heavier than the w201 (at least the manual ones). I recently measured my w201 (16v based) with the m103 3.0-12v turbo motor and it was 1300kg . Browsing the net I see that the early 300E/300CE with manual transmission weight about 1340kg - 1390kg (if these numbers are correct of course ) , so a 16v box in such a w124 should holdup as good as in a w201

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190E 3.0-24v (M104 980) turbo @ 0.8 bar
1/4 mile: 2.483 / 13.540 / 175.17 km/h (street tires)