Haha, I just got the theme of your "Nice Road Trucker" thing. Good show, but I can't stop watching "Deadliest Catch".. don't ask me how I relate those two shows together.
Anyway... I second the idea of an 8.8" transplant from a mustang. You will have to switch your rear rims to make it cost effective, but you can get at least 2.73's for an 8.8". I have an 8.8" in my mustang and it withstands 550hp launches on slicks consistently w/o breaking.. the stock 28 spline axle's are another story, but they will hold fine if you aren't beating on it... which somehow I doubt you would be, given that you're getting almost 27MPG in a 350.
Edit: come to think of it, I remember reading that some Excursions had 2.73's.. maybe something worth looking into also.