Can someone tell me where did this Holley 1920 come from?

Sedanman said
64-72 used the 1920

First year for the 1920 was 1962. Last year for it was 1973. There were many differences some significant, some trivial in Holley 1920 carbs across that year range and throughout the different applications (auto/manual, car/truck/van, with or without A/C, various emission packages, etc.).

I've never noticed any differences in the manual or auto carbs

Internal calibration, location of spark advance port within carb throat, sometimes presence/absence of dashpot.