I'm experimenting with LED bulbs now (interior only).

My goal is to change the dash and instrument lighting to red, at a brightness level that's makes the instruments visible.

The issue with our W123s is that the 74 series instrument (rice grain) bulb has a nearly omnidirectional illumination
pattern, and the light-pipe and fiber optic systems we have rely on it. The LED bulbs have a much narrower
viewing angle (most of the light comes out the front). I'm experimenting with mods to the bulb lens to get more
light out the sides.

For any given light output, the LED bulbs will be 5x to 10x more efficient. Less heat, and no more melted instrument
cluster plastic.

__________________
Bob
'82 300D Petrol B-G Metallic