So your car has crappy instrument lighting at night? If you don't want to upgrade to LED's, you can start by replacing your instrument cluster bezel with that of a 1990-1995 W124. See the photos below for comparison of the illumination prisms:
Even if your bulbs aren't burnt out, replace them anyway. Mercedes Benz part number is: N072601-012240. You can also use Sylvania 2821 (W3W) bulbs. They're the same thing that Mercedes sells you, just cheaper and readily available at your local Kragen, Autozone, Napa, etc. And yes, they are actually made in Germany. DO NOT under ANY circumstances use a 5 watt 168 or 194 type bulb. They WILL melt the illumination prisms. Also, STAY AWAY from anyone selling a Mercedes "Xenon" dash light upgrade kit with those BS blue tinted "xenon" bulbs. Those are 5 watt and as mentioned above, will cause damage. Below is a photo of what happens when you use 5 watt bulbs. The lighting prism will also turn a funky brown color (a bit hard to see in the photo)
http://w124.f0e.net/124_illum/