[unruhjonny]

Originally Posted by FunctionalShaker

... Also, when the small fuel/volt gauge bezel rings went from thin to thick/shallow to deep?
...
To clarify: From looking at later bezels, it appears that the thin rings were replaced by the thicker style at some point. Just wondering if we know when?

...

I believe you are mistaken.

the aluminum turned dash insert used on the Trans Am's always used the "thick" gauge rings - always.

The 70-72 non-TA wood grain dash insert was actually a wholly different part, which had formed openings for the center gauge cluster, and this is why the two large, and small center pods used a thin ring;
If either of the rally gauge options were ordered, the rings used for the separate pod were the thick style rings that the TA used - albeit left in as molded black.

As i see it, essentialy for the 1973 model year there were two things done to streamline Firebird dash insert production;
1) the two small openings for he wiper switch were replaced with a single larger opening (probably easier to manufacture and assemble)
2) the Trans Am and non-TA dash inserts both used what I see as being the same stamping for the back of the dash insert - this necessitated that they all used the same style gauge rings