What does the catalytic converter look like and it location on 2002 grand prix gt?

The catalytic converter on a 2002 Pontiac Grand Prix GT is a cylindrical metal canister, usually stainless steel, that's roughly the size of a large coffee can or slightly bigger. It might have some heat shielding around it. It's typically coated with a ceramic material.

Location: On a 2002 Grand Prix GT, you'll find the catalytic converter(s) in the exhaust system, underneath the vehicle, somewhere between the exhaust manifold and the muffler. Because there might be two (one for each bank of cylinders in the V6 engine), they're likely located fairly close to the engine, towards the front of the vehicle's underside. To be precise, it's likely positioned close to where the exhaust pipes merge from the engine's exhaust manifolds. There might even be two close together.

Important Note: You'll need to get under the car to see it. Always use jack stands and follow proper safety procedures before working under a vehicle. Never work under a car supported only by a jack. Also, the exhaust system gets extremely hot when the engine is running, so let it cool down completely before attempting any inspection or work.