2004 Scion xBI had had the same question in mind!!
You mean the 4.6? There was also a 5.4 IIRC, but I don't know of a 4.9 made by ford. There was a 5.0 back in the day, but it was never in the Expedition that I know of. The 4.6 is an OHC modular V8 engine, one of Ford's better designs to be sure.On my own time, a 1997 Ford Expedition with the 4.9L V8.