Regarding actual FREEWHEELS (not cassettes)... were there any 6-speeds with 12 tooth cogs?
I believe even the early Shimano 7400 series (Dura-Ace MF-7400)
6-speed freewheel was only available down to 13 teeth (and that was around 1986)... and the 7-speed MF-7400 could add a 12 tooth cog.
Were there other 6-speeds freewheels which ever used 12t cogs? ... Regina? ... Maillard?
By the way, here is a gold 5-speed corn cob freewheel dated August 1980 with 13-17 cogs