Denial

Just wondering does anyone know the build dates of the Pet style Keyboards on the early production Vic20 systems?

I don't think the substitution of parts was well controlled or documented. The registry may give you an idea of when the change over happened but there are probably outliers

https://cbmvic.net/registry

We know the PET keyboards were present on the VIC-20 at its release in 1980 (and the VIC-1001 in Japan).

All I can tell you is from my own personal experience: when I got my VIC-20 for Christmas in 1982 it had a Helvetica type keyboard. So that tells me that two years after the launch Commodore (at least in Canada) had already moved on from the PET style (Microgramma), to the Eurostyle font, and onto the Helvetica narrow font.

But I agree with srowe. Knowing how Commodore operated they probably had loose units of older keyboard styles stashed here and there that they continued to use up after the official switch to the newer style.