honestly, the guys over at the Corvette forums had this right. Forget replacing the "bulbs" with more "bulbs" and replace them with LEDs so that you won't have to worry about them going out again for 30 years or so. Just put a resistor in line with a white LED and make sure you have the polarity right.
I plan on doing this to my own radio and HVAC unit over the holidays. They both have several bulbs out but I'll be darned if I'm replacing them with more filament bulbs...
Here's the thread. Guy used blue LEDs which I wouldn't do here, but you get the idea...
http://forums.corvetteforum.com/c5-g...p-warning.html
PS - I know this works because we did it with my brother's corvette HVAC unit about a year ago. Looked great when we were done.