Can't Handle It ~ No Music

I lately recieved a car from my Divorce, the stereo Code is no where to be found! The face plate on it says Acura and inside the stereo says Pioneer so for one I don't know what kind of stereo I'm really even dealing with, And How could I go about getting the code for it?
All I really know is~ NO- Serial # on it any where, AND it asks for a 5 digit code! Can Anyone Help?????

The brand of the stereo is Pioneer. About the code, look for a booklet in the car which says Pioneer on the cover, that should give you an idea about how to deal with your problem, since I am not really familiar with Pontiac's, that's all the info I can give you for now ;)