Air Cleaner Base and Hose ID help

[brandosaac]

Plan on listing these for sale shortly and wanted to confirm exactally what they are.
Is this an original 68 GT350 air cleaner base and hose , or was it also used on other models ?
thanks

[brandosaac]

pics

[Coralsnake]

GT350 and GT500 are same and they appear to be originals

[Wedgeman]

When in the production line did they switch from the center bracket on this base where the bolt screwed into the center of the carburetor, and the one where you drill a hole in the lid ?

[Coralsnake]

The Tech letter for reworking the air cleaner is dated March 14, but I suspect the change was much earlier