As for 1st gen's I don't know, but my 2nd Gen had a green color built into the plastic that backs the gauges. Think of it this way. Take a green piece of plastic, paint the black background and lightly paint the numbers. When there is a light source behind it, what color will show? The green from the numbers. If you take blue piece of plastic and paint whatever necesary and replace it with the factory when the lights go on, the blue will show. But the whole trick is painting everything to scale/proportion/size.

K, I've got a question.

My gauges have a tint of green to them. So my question is, if I get bright yellow bulbs, yellow+green = blue.

Correct me if I'm wrong please!

Blue is a primary color...
 

You can't make blue by combining colors because its a primary color. Blue, yellow, red...they can't be made by combining colors. Yellow and green will just make yellowish green. You'll only get different shades of green without replacing the whole gauge. There is a layer of green built right into the back of the gauges, so unfortunately there is no way around it.

Re: Blue is a primary color...
 

Hmmm, I'm gonna blast it with bright blue then... hehe

1st gen
 

Those are red bulbs in the middle, blue on the side (they don't look much different than green).

Sorry for the bluriness, it's shot in the dark, for obvious reasons, which the camera doesn't like too much.

http://members.cox.net/chastan/reddialsm.jpg