I'd return it based on this pic alone. The regulator is a cheap, non Bosch unit.
How do I know? An alternator rebuild place gave me one for nothing and it does not look well made. Very different design than Bosch, with parts potted in Epoxy. I'd return it for one with a Bosch regulator.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked