This is the first 220 one I have seen of theses as well.
As to factory/Holden related or not that is still something I am still trying to get to the bottom of.
I have been told no by a few people but my ex boss worked at a Holden dealership here in WA (Melville Motors) in the 70,s and
one of his jobs was to fit them to the speedo's.
So not factory but carried out by at least 1 WA Holden dealer ?.
Cheers Paul.