2004 Engine 5.4 or 4.6?
Ford has no plans to put a diesel in the F-150's (heard it on a Ford conference call available on their web site). A reporter asked and they said no.
The milage on the 4.6 and the 5.4 is teh same according to the info I've seen. I'm definitely going for the 5.4 for whatever more it costs up front. It will be worth it.