Through a number of cross references and searches, I found this:
Bosch # 1235522060
BMW # 12111353117 superseded by 12111351446
Also used by Mercedes and Volvo up to 1971
A “made in Germany” part is available at Rock Auto brand name Bremi, for $13.08
KARLYN / BREMI / STI 228017P
https://www.rockauto.com/en/moreinfo.php?pk=3874509&jsn=601
My car is still “in process,” so I haven’t tried this one yet.