W124 Lighted Head Light Swtich Knob?

[Benz Mondi]

On some W124's the middle of the stem that the head light knob is pushed onto has a light bulb that illuminates the orange center of the knob itself. Some do not have one.

Anyone know which knobs from what year cars have this?
Source for the bulbs?

It's always bugged me that looking at the knob at night (other than full headlights on), you can't tell what position it's in. I want to allow for the light from the stem to reach a small hole at the tip that I would create as an indicator.

thanks.