Is a 2002 grand prix gtp also compatible with.parts to a 05 Pontiac grand prix both have the 3.8L engines? Or vise versa?

The 2005 is fully operational.

97/03 SAME CARS 04/08 SAME CARS ENGINES/TRANNY/COMPUTORS DIFFERENT SHOULD STICK TO 97/03 CARS

Thank you, how different are the engines since they both are 3.8L V6 turbocharged? I understand trnnay computers & stuff, I've also been searching on here for vehicle's to purchase. Are the motors just styled different with different components is why they wouldn't match even though there the same engine.

None of these cars are turbocharged. The engines are all 3.8 but there were two or 3 different series used and they had internal and possibly external differences which make them different engines. The GTPs had a different engine again to accommodate the supercharger they came with.