The external-regulator GM unit was known as a "Delcotron 1-D". I've tried to find some good pictures of each variety, but so far nothing wants to upload to my photo host site properly. Just search the following names:

Delcotron 1-D

Delcotron 10-SI

The differences are pretty obvious. The two blade terminals on the 10-SI are part of the internal regulator. There's a way to bypass the 10-SI regulator to see if the alternator or the regulator is responsible for a "no-charge" problem, but trying to describe the procedure without pictures or a video is sort of confusing.
Jerry

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