I had a truck apart recently and for fun used all leds in the dash.
I got prewired 12 volt leds off ebay for cheap in all sorts of colors.
Used milk containers, and other colored plastics like for folders as diffusers and tested everything in the dark.
I had supplies and drilled through existing bulb holders and used hot glue to hold things in place.
I found through allot of experiments that most of the time bright white leds sanded against stock vw color panels gave me the best light. Even moreso than sometimes multiple leds of that same color which was really interesting to me ?
I was happy with everything, love the clarity at night. I think one switch in the dash did not agree at some low power point with lighting up, maybe it was flashers i dont remember.
I wouldn't hesitate to do it again. I got 100 leds for less than $20 to door and had the other supplies laying around. So some time involved but with number of leds it was way cheaper than some of the online stores i was looking at as far as the drop in types. i also used my custom setup on heater controls, cluster bar, etc.