I have wondered this myself. My guess is yes, they are legal, since there are a lot of cars out at the moment with clear turn signals, I think even some commodores come with them.
However, most have an orange film on the inside which, when illuminated, makes the orange light, whereas the d-speed indicators use an orange globe. I doubt that would have any effect on their ADR status though.
I would be interested in a group buy depending (heavily) on the price. Perhaps we should get Rezz's input since he sells them?
LW.