I've got an 89 F350. 7.3, ZF5, BW 1356, 3.55's with a Posi rear. It started life as a F250, 2wd with an automatic. Got 24 MPG exploring this weekend. Fixed the A/C today.
My list of Have-To's is getting shorter, just gotta put a muffler, glowplugs and a shifter boot ring in it. Then the plan is whatever camper shell I find in the free-to-cheap range, a set of 285/75/16 BFG ATs and a bumper (or front receiver) for my 8274.
I got into 4x4s for the exploring, then followed the path towards "extreme". Now, I'm getting back to what I originally wanted to do. I bought a Delorme's atlas and my wife and I go dirt road hunting every weekend.