[shorod]

Yep, those schematics all show changing out a zener diode on the base of the pass transistor to regulate the voltage. Those schematics are pretty much doing the same thing as an LM317 with pass transistor.

As for finding new alternators with external regulators could be a trick where you live. I don't have a particular part number in mind. I just remember helping Dad with some Ford cars that were older than me and had an external finned box mounted on the fender liner. Dad said it was the external voltage regulator. You might check what was in a 1968 Mustang or 1970 Torino, then see if either of those are available where you live.

If you are storing the charge from the 36V alternator in 3 series car batteries, then the batteries will probably provide enough filtering that you would not need the capacitor.

-Rod