Don't know about part numbers, sometimes they change due to revisions and design changes. Also part numbers vary a lot between ACDelco and Chevrolet numbers.
I've found a replacement for you available form autozone, a bit pricey though
CLICK HERE
EDIT: I just looked it up and found out the switch was used in grand prix and sunfire vehicles; I'm guessing it should be easier to get one from a sunfire than finding a 2 door GP; I haven't been able to find one around here and I'm in need of the same switch as yours. Now that I know it I might try searching the junkyard for sunfire's.
Oscar.