Do the Oasis report...if its good go get it. 63,000 miles is nothing for a 6.0. Once you get it and to maintain longevity, use a quality synthetic from Mobil 1, Rotella T, or Amsoil, and change it every 5,000 miles, change the fuel filters every 10,000 miles, clean the EGR valve every 10,000 miles, do a full radiator flush and fill at 100,000 miles.
The tranny has to be flushed every 30,000 miles. If you keep up with the maintenance and stay away from tuners that have crazy 150+ hp tunes, your rig will last you a VERY long time, even pulling heavy loads. I keep up with the maintenance on my '04, I have no headgaskets or EGR cooler deletes, and I do not have a tuner. I have 85,000 miles and consistently tow heavy loads ( front loaders, tractors, bob cats) from FL to TX, I own a land excavating company.... NOT ONE SINGLE PROBLEM TO DATE
'07 F-250 PSD 4x4
. S&B, 5" exhaust, zoodad, blue spring, '03 Turbo, 6.4 starter, 2.5 f/coils, adj Trac bar, 2" r/add-a-leafs, egr delete, DC Power 185, Procomp shocks, SCT SF3 tuner, F-Detroit Truetrac, R-Detroit Locker, 4:10 gears, LT315/70r17 Duratracs, Amsoil Gear lube, Amsoil ss fuel efficient ATF, Delo 400 LE 5w30 diesel, archoil 9100/ar6200, bpd ficm, arp studs, oem gaskets, HD water pump, stc, plugs, stand pipes, 6.4 banjo bolts, monitor, new oil cooler, coolant filter