Barry,
I had a '98 Eddie Bauer Expedition (loaded of course, 5.4, AODE trans I think) up till last year. Dad bought it used in Delmont back in '99. Sold it with 124K. Had no mechanical engine or trans issues ever, aside from it appetite for gas! It lived a clean life on a concrete driveway when parked.
Sure, fairly large year difference 'tween yours and this one, but still basically the same generation (1997-up).
With that being said...
What the long term sore spots turned out to be:
- Remove and cup wheel the rear control arms. They are a powder coated (or a thick paint) U-channel and will delaminate. Mine had giant holes in them. The rear literally was ready to fall out from under it. Fabbed new ones out of 1x2 tubing using the OE bushings. Track bar was almost as bad, ended up boxing it at the ends for stiffness.
Aftermarket "performance" arms are available on Ebay... hmmmmm.....
I think your setup may be different than the '97-up ones, but still check it out.
- Rear differential, exterior... Cup wheel that bad boy too. Mine had mad, cleaving rust issues. I worried about its strength (9.75" rear, w/ 3.73's) it was so bad.
Coat all those components with something greasy and non drying inside and out.
- Engine block. Since the gaskets don't leak on modulars, there's no goo to keep the water jackets in preservative. Same goes for the differential, since it doesn't get any of the spray either. Have heard of one shop (didn't actually witness it) that had a Explorer 4.0 that had rusted from outside in and leaked antifreeze... Ford wouldn't help them.
My block was scary rusty when viewed through the wheelwells.
- My rocker panels (and other sheetmetal) actually stayed in pretty good shape. Most aren't as lucky. We sell A LOT of rockers/cab corners/rear wheel arches for GM, Dodge and Fords... have delivered some for '08's in body shops... Spray more greasy stuff up in there!!
- Exhaust manifold studs. Been a problem on modulars since '97, and no recall. Go figure.
Dorman sells complete replacement kits. Hmmmmm again........
- Front driveshaft. Remove, clean, coat. Mine was VERY crusty. Probably coulda easily poked a hole in it.
- Starter motor. Remove all the wires, clean terminals and coat with lots of dielectric grease. I had corrosion problems, and our controller at work had the same with his 2006 Exped. Hardware on both trucks was bad crusty. Must be the proximity to the RF wheel spray.
- Neutral safety switch. Located on the trans shifter shaft. They are plastic, but get dry and bound up to the point of not being able to move the shifter on the column. Galls to the shaft and gets trashed if you pry on it too. Oil the daylights out of it. No, I wouldn't have thought of that one being a PITA either.
I have a super clean '99 Suburban now... has the SAME issue, along with the wickedly rusty rear diff. Crazy.
Other than that, we had real good luck with the truck. Change oil @3k, you won't have any issues. I may have a trans filter and maybe some oil filters I'll drop off to you. I need to (ahem) do sales calls out your way anyhow...
Congrats, you're gonna like it!