There are no available adapters that would convert your flat bar receiver to a 2 inch receiver, nor is there a 2 inch receiver available for the 1996 Firebird.
The Class I receiver you mentioned, part # C11117 is compatible with your vehicle, but the hitch will not fit models with dual exhaust or single exhaust models that have the bumper with two cutouts for the exhaust.
You can see the install details for the hitch by clicking on the provided link. view full answer...
Yes, the Curt hitch part # C11117 is a confirmed fit for your 2002 Pontiac Firebird and would work well for you. For trailer wiring you'd want the universal style kit part # 119178KIT which has been confirmed as a fit as well. view full answer...