Well I have a 1999 Ford Expedition XLT and I had the same bright idea, that some of you have had, that i was going to swap a newer engine in the older truck. Well I found my engine, 2002 Ford 5.4 Triton V-8 with 1000 miles on it, sweet............ah no. I was told it was an '02, well when it came,it magically turned into an 2003 Ford 5.4 Triton V-8 with 1000 miles (thanks Ebay). After the flying car parts

and the months of no one (Ford) knowing or wanting to talk about swapping an '03 into an '99. I found out that I would have to change the ECM, UNDERDASH wire harness and my exhaust system (maybe, still not sure

). The 98-02s (f-150, expeditions) are relatively the same engines and will swap. The 03 f-150 might swap over but I have too little information. The 2003 and newer expedition and f-series engines will require some modifications (computer and underdash wire harness) to fit in an older truck and a bit more money. So...............If you still want
to swap engines I have a
2003-05 Ford 5.4 Triton V-8 with 1000 miles for sale.
Good Luck Guys
ps.
this website might help you decide
Ford Truck Specifications - F150, Ranger, Expedition, Excursion, Navigator