Changing Dash Light...

You need to pull the guage assembly out. It's not hard at all. You'll need to pull the headlight switch, then the trim piece in front of the guages. Can't remember if it's a screw head or small bolts. You'll see it when you look up through the steering wheel. Then there are 4-6 more smaller bolts that hold the guage assembly in, you'll have to undo the speedo cable and two electrical connectors that plug into the guage assembly. Once you have it free, you'll be able to see the little light bulbs in the back of it.

No way to do it without pulling it though, I don't think.

http://www.stangnet.com/reviews/macgauge.html go here and follow every step, when u replace the bulb im guessing you pull it out an put a new one in.