My question is will a 3800 series 3 supercharged engine from a pontiac grand prix gtp. Fit into a 1999 pontiac bonneville sle perfectly with out any modifications? If not do able how can i make it work :?:

You will need the engine, transmission, engine/trans wiring harness, both axles (maybe only one though), and the PCM from the donor car.

Complete.

if you just want the motor....

you can use a Bonneville L67 Wire harness, Trans, and PCM...you will also need to get an adapter plate for the Throttle body, because the Series 3 uses a drive by wire TB and your Bonneville dosesnt....but there are vendors out there that sell the adapter no problem

i think he only wants the engine and as far as i know you will only need the engine, adapter for the bonneville TB, and the PCM because the series 3 does not have the same PCM but you may have a problem with motor mounts (i am not sure) because the 99 bonne is an h body. the Grand Prix is not.

motor mounts would not be an issue as he can use the ones that are provisioned in the block....remember the BLOCK of the Series 2 and 3 are exactly the same

He will also need to procure some L67 fuel injectors.