My wife is driving a 97 Expy 4X4. I was looking around on Ebay for stuff a few months ago, and saw an item that had all 8 fuel injectors, and a K&N intake, of a 5.4 Expy, used with around 30k miles on them. The K&N intake is like $300, and this was around $70, so I went ahead and got it. I E-mailed the guy a few times, and it turned out that he had gotten a complete SC set-up out of a wrecked Harley Davidson F-150, and had installed it on his Expy (he didn't say if it was 4X4, or not). He said it was a blast though.
Brandon
By the way, I can't say the K&N added any performance, or mileage, but it definately sounds sweet (very pissed off).