How do I replace instrument cluster lightbulbs?

Your instrument cluster will need to be removed and possibility sent to a repair facility to have the bulbs repaired. Most of the newer clusters do not have easily replaceable light bulbs.

these light bulbs are soldered in , you can go to the dealership and they can order you another one ,but what i did was went on craigslist and found a guy who does mobile service he also fixed my cd player and changed the knobs on radio.

This is very common on the 03-06 GMs. The bulbs are soldered to the circuit board. You can get it repaired here - www.drspeedometer.com