Rupp model K number stamping in floorpan & front axle

[Dan Reed]

I've been restoring a Rupp Model K Foreign Enduro and had removed the original floorpan with intentions of building a new one when I noticed on the bottom of the pan on the right front corner there was a #12 stamped into the pan. When I turned frame over to hold the pan up to where it fits to the frame, I noticed the same #12 stamped into the front axle directly to the right of the #12 on the pan.

Does anyone know the significance of the number stamping? Is it some kind of coding of when it was built or where it fell into a production run coming off the line?
Thanks,
Dan