Hit the store, they'll know which one you need. You could also do a search on
www.dixiemontecarlo.com
www.summit.com
and get the actual part number.
You will have to take the dash apart to get at that bulb. I did this project on my 80 not to long ago. Remember you car is over twenty years old. You start moving thing around and Murphy sneaks in. Buy some extra! Get your hands on some emery cloth or some 400 or 800 sand paper. The cooper strips that make contact on you bulbs will be tarnished. You will have to remove all the bulbs to clean them but better to do it once right than have to pull it apart later because some of the others stopped working. This happens often because the bulbs do not sit exactly where they were for the last 22 years.
good luck