Larry:

I believe the voltage regulator is just above the plug where the wires are. I can't check right now on my 300D, but you will need to pull the tray underneath to reach the alternator, probably. It is on the passenger side down low, not accessable on the W124 from above.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!