Not only the 149 underwent various changes over time ...
Since the 146 was first produced in 1950, it changed a lot and even went out of production for a decade.
About a year ago, when I wanted to date the used 146s I was buying, I started this spreadsheet.
And as I learned a lot in this forum, I'm happy to share the gathered information - as suggested by siamackz, carlos.q and sanfong, here is the the extra thread on it
If you find any mistake or have new information, please share. I'll try to keep this doc updated.
PS: thanks to DKbRS for the inspiration with his dating 149s thread & chart
Edited by neugeekig, 28 June 2018 - 19:22.