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Can -- for example -- Miraphone rotor details be used to (very vaguely) guess at the age of a tuba?

Like, did S-links change to miniball quickly over a couple of years, or did new models get them before older ones changed?

Was the engraving on the rotor caps a feature that came and went at specific times? Or did some models have them at the same time that others didn't?

And when did keels go away?

The keels became shorter in the late 60’s/early 70s, and DVS linkage (adjustable nylon socket on a steel ball) was introduced around that time as well, which was before sealed bearing links, yet – in my opinion – just as good.
S-arm linkage featured nylon bushings as early as the mid-1960.
Smaller gauge stainless steel outside sprung lever springs – rather than larger gauge nickel silver ones – also began to appear in the 1970s.

There have actually been quite a few changes, and quite a few very short-lived “let’s try this-es” as well.

Trying to remember all of this stuff is sort of like attempting to list all of the exceptions in English grammar and spelling.