Joel, here are a couple of emails from Antonio Esteves (esteves7@gmail.com) (Portugal?) from my earlier research into options for my '29 101.
22 April 20:
First would need to ask if you're looking for a DU5 or a DU7.
Second if you're in need of an alternator, at 12 volt output, at the price of 430€ ( your price ) plus shipping. ( it weights less then 2 kg.) or, an standard generator, priced at 760€ ( your price ) plus shipping. The gen is std 3 brushes, w/ electronic cutout, (for electronic regulation add 50€, in which case they work 2 brush system).
For the dU7 generator, orders are relatively delayed in time and can´t say exactly when, but most probably into 4 to 6 weeks from order. For the alternator, i had the news that my parts from laser cut will be ready this week so, 2 to 3 weeks expected delay ( the same for a DU5 gen).
Looking forward your news,
Best regards,
António Esteves
10 May 20: If we talk about generators, there is the option between 6 or 12 volt, no matter DU5 or DU7. that are equally priced.
The DU's perfor very similar. It's only a question of respect for the correct period fitting. DU7 is a bit more technically evoluted but they perform similar and share the very same inductor and armature.
According to application chart until March 28 it was supposed to be the DU5. From there, DU7 but... not always... I think they were putting away what they had in the shelves before changing the model.
In the past i had alternators working under the 6 volt system but i can´t get those rectufuers/regulators at the moment.
I'll be happy to assist on any other related question.