can someone please tell me if 2000 2001 or 1999 5.4 liter engine would fit in a 1997 e350 van if the donor vehicle was also a e350 van if not what is the difference

 

The engines will all physically fit in any chassis from '92 and later. The Modular Motors which include the 5.4 came along beginning model year 1997 though.

Swapping engines is the easy part but you will need to re-use the ECM, sensors and wiring harnesses from the original van in order for everything to work properly.