I've found good ones on flea-pay on several occasions and they were NOS. They don't care what the voltage is. It's just a set of flyweights that act on a central rod which in turn opens or closes the switch. There is not much there at all.
I haven't paid this much for one but it is NOS.
https://www.ebay.com/itm/NOS-Thunder...QAAOSwIKVd9fgV
There are others and some are good used. All the Borg Warner ODs used the same basic governor for the most part.