The 7.3 Powerstroke was replaced by the 6.0 Powerstroke about midway into the 2003 model year. And subsequently used in Ford Super Duty trucks, vans, and Excursions until the 2007 model year.
Whereas the 6.0 Powerstroke's older brother the 7.3 would become a diesel enthusiast's darling the 6.0 will go down in infamy as being one of the most problem-ridden diesel engines of all time.
But at the time, and in order to meet lower emissions standards, Ford decided the 6.0 Powerstroke engine would be better suited than a redesign of the 7.3. The 6.0 would have EGR—exhaust gas recirculation, a "better" fuel injection system, and a redesigned turbocharger.
After recalls, numerous TSBs and owners encountering a host of 6.0 Powerstroke problems including: blown head gaskets, failed oil cooler causing cracked EGR—Exhaust Gas Recirculation—coolers, failed EGR valves, sticking turbos and failed injectors.
But Ford wasn't just chasing the whims of the EPA and CARB. GM had since released a more powerful Duramax and something needed to be done. The 6.0 came with higher pressure HEUI—hydraulically activated injection system—with 600 psi more than the 7.3 HPOP could put out. This delivered 325 hp and 560 lb-ft of torque.
My own experience with a new 6.0 was more power, faster acceleration, and increased towing capability. All seemingly good things that unfortunately were short lived and came with a maintenance cost.
Regardless, bottom line, oil temps on a 6.0 Powerstroke are at the root of much of the 6.0's bad reputation for catastrophic failures.