Will a transmission out of 2006 Pontiac grand prix gtp work in 2001 gtp?

No, a transmission from a 2006 Pontiac Grand Prix GTP will almost certainly not work in a 2001 Pontiac Grand Prix GTP. While both are GTPs, the significant model year difference means substantial changes were made to the drivetrain and its associated components. The transmissions themselves are different and incompatible. Even if the bolt patterns *seem* similar, the computer control systems, bellhousing, input shaft, and other vital parts are likely incompatible, resulting in a non-functional or possibly damaging installation.