Josh Welcome to the forums.
Without having one key fob with the FCC ID #* or the GM/Uta #* from the back of the vehicles key fob it can get a bit tricky.
I am wondering if GM may be able to provide you with such information specific from your VIN number to look up.
There are sites like this one that may be accurate though?
Pontiac Key Fob | Pontiac Remote Starter | KeylessRemotes4u.com
I am not so sure that I would want a used one considering it is a wear item, and that you have to rely on it, and program it.
I have discovered that you can call some local automotive locksmiths, and they can offer new generic remotes or even use the correct GM remote & program them for a nominal fee.