How to Determine Alternator Make w/o Disassembly

[grizzfan]

There have been several alternator problem threads over the past couple of months but nothing helps me solve my particular problem/question.

I ordered one of those cigarette lighter volt meters which seems to work fine and I did so because after tightening my fan belt I still couldn't get my alternator light to go out. The meter reported very high voltages in the 14-16v range, Somewhat proportional to RPMs

So I bought a new Bosch regulator, installed it and for a month the voltage was more reasonable, in the 13v range. That has all changed and we are up to the higher voltage ranges again. (Batteries, Interstate U911, seem OK).

Then I remembered the engine decal warning that the alternator and regulator must be of the same manufacture. My regulator is external to the alternator.

As far as I can determine there are basically two manufactures of alternators for older Porsches, Bosch and Valeo. How do I determine who made my alternator without taking everything apart? Of course I could buy a Valeo regulator and see if that works.

Thanks in advance.

Tom