Easy your looking for a 145.022-74. Which may have been made in 75... there are some resources to verify it’s production date though with a serial number. Ilovemyspeedmaster.com
I’ve got a 145.022-76 as a Birthyear watch.
This link should help and feel free to reach out to me. I’ve studied the 145.022-74 and -76.
This should be a good start.
http://speedmaster101.com/145-022/145-022-71-74-76-78/
Some help
DNN means Dot Next 90 and refers to the dot near 90 on the outer bezel. Later incorrect bezels also have the same dot but are called something else earlier ones had the Dot over 90 aka DON.
Step vs some dial refers to the ridge just inside the minute track and not the subdials. This trips up a lot of people at first.
-74 was made between 74 and 75. The next sub reference is -76 which was produced through 1977. Both the -74 and most -76 have a unique dial where the S is speedmaster does not drop to the level of the bottom of the p, and the tail of the r drops below the word speedmaster.
BMW owner here also. Not my e9
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