To add to this growing subject of study have the following to offer
Appears that at least San Jose used two different vendors for at least part of the year. This may help explain the variations of finishes or maybe not but the major purpose of the post is the two different styles/designs made and used.
At this point just posting for considerations. Both examples are fairly close to one another
5R1473xxx - On this car a pair of each version was used. Not something that could be easy to see once installed
5R15089x - Looks like a makers mark stamped on the surface of the plate at about 7 o'clock. Notice you can see a stamp in the third (from the top) one in the picture above also though different loation
Also take note that we have versions posted with "flat" square ends and those that are pointed if we look at multiple plants. Maybe we have a difference between 65 and 66 or a running change somewhere. Might be visible on an assembled car on the outer post