I have a 1997 F250 Powerstroke with 250,000 miles on her and pull a 37' fifth wheel. All I have done to the truck is a tuner, intake and exhaust. I pulled about 10,000 miles last year and it does a great job. You will not be the first one to the top of a 10,000 ft pass but you will get there. The only problem I have is keeping the EGT down on long hills, I have an intercooler ordered to address that issue. The best part about the 7.3 is they are pretty much bulletproof without all of the problems associated with the newer, more complicated diesels.
Can't comment on the newer 7.3 but hope this helps.
