Hi Dennis,
Also, in going from 6V to 12V, if one has a Rexaco oil gauge w/light and Rexaco temperature gauge w/light, they are made for 12V; however, they will illuminate with 6V, but their interior illumination will be dim.
Bert's sells LED dome light and LED dash light bulbs that will work for 6V or 12V.
If LED tail/stop lights are 6V, they will not work for 12V.
Most Model A parts suppliers are aware of required items to be changed or altered if one switches from 6V to 12V and vice versa.
But Dennis, I think most Model A owners were born with 12V; but after we age considerably, we slowly slide down to 6V; so if you ever come across a Medical Magazine Advertisement for a Human-Resistor-Boosting-Device to boost us Model A owners back up to 12V or more ........ please let us all know ...... feel like I could use an upgrade!