Voltage Regulator Location
 

Maybe I'm missing something obvious, but I can't see my external voltage regulator and it's not listed in my Haynes manual electrical diagrams...

I have pictures included of the type of regulator; does anyone know whereabouts this is located and if there are any tricks I need to know to switch it out?

Look at the back of your alternator, it is held on by 2 screws and holds the field brushes in place.

Different type
 

No, the type of voltage regulator I have is not the type that plugs into the back of the alternator, but a more boxy style which is called "external." I have a picture of the type attached, maybe you can still help me?

BOSCH Alternator.

Unless your regulator system has been altered with a different regulator, the regulator on your car is attached with two screws on the back of your alternator........if I remember, it is oval shaped.

Herb
'82 240D
'87 300SDL
'92 2.5 Turbo

In the 70's, (and maybe into the 80's, I'm not sure) Bosch supplied alternators with external regulators such as the one showed in post#3 here. A few are still in service (my 76 Volvo had one) but most have been replaced by the internal type. If your vehicle originally had one, it's likely been replaced if your alternator has been in the last 10-15 years. Typically 3 wires lead from the back of the alternator right to it, so if you don't have that, your alternator has already been converted.