Interesting. Sometime ago I was searching the interwebs for the answer to this question and an advanced Google search did find this:
<Engine Weights & Sizes>
If you scroll down to the Mercedes section it lists "inline six 1995 and back" at 441 lbs. So considering the repair manual lists the dry engine weight at 401lbs (182 kg), the extra 40lbs. would account for all the accessories (of course by 1995 the sedans obviously had more accessories than a 404).
<Engine Weights & Sizes>
If you scroll down to the Mercedes section it lists "inline six 1995 and back" at 441 lbs. So considering the repair manual lists the dry engine weight at 401lbs (182 kg), the extra 40lbs. would account for all the accessories (of course by 1995 the sedans obviously had more accessories than a 404).
