Whew! I just finished reading your entire thread, and I am impressed with all you have poured into your truck, both time and money. I just picked mine up last weekend, so I've mostly worked on cleaning out dog hair and trying to minimize the smell of wet dog/cigarette smoke...not a great combo I must say. Mechanically, she's pretty sound, although my muffler looks a lot like yours before you bought the clamp, so that will be my first priority. I did the cd changer delete today. Also the rear window driver's side hinge was missing the gasket that goes between the hinge and the glass, so every bump caused a loud rattle. I tried to find one online but apparently hen's teeth are much more common, so I dug into my fly tying materials and found a piece of black closed cell foam the right thickness and made my own gasket...no more rattle!
Unfortunately for me, unlike Colorado, Iowa seems to have a never ending supply of salt, which is liberally applied to our roads, so my rocker panels are crap. That will be my summer project. Otherwise, I'm in pretty good shape mechanically. The interior, while relatively filthy, isn't too bad except for the redneck repair job to the dash/radio surround. Apparently while installing an aftermarket stereo, some nimrod pried the plastic off and wrecked the tabs that hold it on. They had an easy solution though...drywall screws! Well, the plastic does stay put and doesn't rattle. The exposed screw heads and cracks in the dash they created don't do much for me though. May have to pay the local wrecking yards a visit one of these days.
Anyway, I wanted to compliment you on all the upgrades to your Expedition and especially on documenting them so well here.