Font change on 3590.50

Hello!

I am looking at a few 3590.50 examples and I have noticed two different fonts on the dials that I see.

There is this one (which i think is on the older ones)

And this one (which i think is from the younger ones)


Can anyone tell me about what year the font changed? Am I wrong about which one is older?

Also, I searched around for a thread that explained the dial evolution of the speedmaster pro, but could not find one (only some comparisons between 2 or three variations). Does anyone know a good place for me to see a comprehensive layout of the changes?

A book called Moon Watch Only.

or the web based version you can buy access to.

Guess I'll be ordering one of those! While I await its arrival, does anyone know the approximate year of the change?

The 2 long S versions were seen first for 2 or 3 years of the 3590, then the short S version was seen up until the 3570 was released ~1997. I doubt there is any price difference in which dial a 3950 has so don't get hung up on it. I like the early long S myself which is like that on the 1980s 145.0022 model.

Thanks @padders ! I prefer the long S also; nice to know it is not incorrect on a 3590.