On this side of the creek MBUS publishes a technical sheet showing all models' specs and dimensions. In the 1991 sheet they show the 300E as weighing 3365lbs and the 300CE as 3505lbs. Of course this is with the M104 engine and larger brakes but wouldn't think this amounts to 140lbs...do you? Curious!
300SE, 300CE, 190/5.0