Join Crownvic.net, they have a huge member base and can walk you through all the steps needed for such a swap. I'd also suggest swapping over the engine and trans as an assembly, and you'll need the CVPI's radiator and intercoolers, then you'll want the engine harness, computer, and sensors, and yes computer will have to be reflashed or go with an aftermarket upgrade. Even something as small as the trans's OSS sensor is subtly different from the GM's and would send wrong data to the PCM, so it's best to keep it all intact as an assembly (and I wouldn't advice mating CVPI's engine to GM's trans as torque ratings are way different). If you pull the GM's engine block and want to swap that out with CVPI's, as a short block or long block, you may still need the CVPI's PCM as timing and cam profiles are sure to be different. Best advice: go to Crownvic.net and bounce it off members there.