Minolta MD Lens Question

I took delivery today of a 100mm f/2.5 MD Tele Rokkor-X. Somewhere I have another one like it and it with either the same name or just the MD Tele Rokkor name. I have the previous 100/2.5 versions except for the very first one with the longer focusing ring. I also don't yet have the final plain MD version. I was surprised that the MD Tele Rokkor-X which arrived today has a metal aperture ring. All of my 50mm MD Rokkor-X and plain MD lenses have plastic aperture rings. I have many Minolta manual focus lenses so I will have to do some checking. Do other MD Rokkor-X lenses have metal aperture rings? Did Minolta phase in the plastic aperture rings?

Here's a site that can probably answer all your questions: https://www.rokkorfiles.com

More specifically: https://www.rokkorfiles.com/Lens History.html

But for what it is worth, I do believe that some of the very earliest MD lenses had a chrome aperture ring.

And here is a compendium chart that parses all the variations within MD and MC versions:
MINOLTA Manual Lens List (eazypix.de)

Bearman said:

And here is a compendium chart that parses all the variations within MD and MC versions:
MINOLTA Manual Lens List (eazypix.de)

Click to expand...

Nice!

Here is another excellent site with details on Minolta manual focus lenses, including the different versions:
MINOLTA SLR LENSES (subclub.org)
General page, where you can get to pages on the cameras and accessories as well:
MINMAN (subclub.org)

Here another one, tests and collection of forum comments about many lenses. Mostly in German (Google translate!), but most of the summaries are in English as well.
www.artaphot.ch/minolta-sr/objektive (lens summary, versions, optical design and collection of forum comments from the German Minolta forum)
http://www.artaphot.ch/minolta-sr/objektiv-vergleiche (tests on digital 35mm & APS-C)