I'm working on a 2001 sts and need to replace the lowbeam bulb. It has a projector headlamp with a bulb-balest assembly. The dealer has no clue on what I need. The number on the old one is not a valaid number and the part he sent me does not have a bulb only new balest.

Try this link:
http://www.sylvania.com/ConsumerProducts/AutomotiveLighting/LampReplacementGuide/AutoLRG-Results.htm.

Hope this helps.