Nothing.
By far the strongest and most reliable truck I've ever owned.
Basic package is stronger, faster, and more abundant than compitition.
I finally pass the rest when I go up the hills.
I have a stock F350 7.3 diesel-8ft box-extenda cab Lariat-loaded.. Purchased this truck new in March 2002.. Now have 85000 km (52000 miles). I have had two problems both fixed immediately by dealers. (1) an injector failed. (2) a hydraulic brake-powersteering line wore through as a result of rubbing on left side front near shock tower.. (suggest everyone with one of these trucks check that hose now for abrasion.. Bad positioning by Ford -but- easily fixed.. This truck hauls without being juiced.. At 100 kmph (62 mph) I experience 24 imperial mpg (20 usa mpg) not loaded.. Hauling my 12000 lb 5th wheel, average 10-14 imperial mpg depending on terrain at same speed. This is a very comfortable truck and drop dead reliable.. Why Ford went to a 6 litre from this tried, tested and true 7.3 is beyond me.. The potential in this engine is there for the taking.. My buddy with a 2003 similar 7.3 also has had no serious problem and gets the same fuel mileage as myself if he keeps his foot out of it.. I would buy another without hesitation.. Always room for improvement though..
They went to the 6.0L due to 2002 emmisions standards changes, it has a variable geometry turbocharger. it is unfortunate, the 7.3l was bulletproof and easy to work on. tree huggers 1, workin man 0!