Yes the encoder ring does not change. I did not mean to carelessly leave an open end here.
A better example: Changing tire sizes. In older cars you had dip switches to flip to compensate for tire size increase/decrease. Later VDO began using color coded plugs that were nothing more than jumpers that replaced the dip switches. Those plugs I think are no longer used today but can be found on 80's BMW's. Without those plugs making changes to the car could mean you needed an interface to correct the speedometer reading. In this manner VDO could use the same guage on many different models of cars.
BD