Looking to Purchase a 5.9...a few questions

If you plan on using the factory fuel injection the 96 up has OBD2 format for the PCM (more tunable). Get the engine harness as well as the PDC (fuse panel). Also get the flexplate if it's automatic, flywheel if it's manual. Most likely automatic if from a van. The flexplate is weighted and different from the 5.2 and older 360 flexplates. Use a neutral converter. The fun part is putting together a fuel system for the factory fuel injection, but it's doable.