03's notoriously have the worst HPOP, so it's possible.

The batteries you could certainly take somewhere else to have them load tested, but it is always best to replace both anyways, and bad batteries will make these trucks run like complete garbage.

It's really tough to say. The dealer could be 100% right, or they may be trying to stick you for some.

I can get 19 mpg on the highway as long as I keep the rpms under 2000. The only mod on my truck is a 4" turbo back exhaust. I have over 145k miles on this truck and it has had its share of 6.0 troubles, egr coooler, oil cooler, head gaskets and studs. I bought this in Oct 04 and my first trip was from Washington to New Orleans pulling a 5th wheel. I travel to and from Corpus Christi, every year. I change all my fluids and filters at regular intervals.

^^^ i hope its hand calculated cause that overhead read out is usualy dead wrong

Just bought my 2006 F350 crew cab SRW and within in days truck lost complete power. Changed fuel filters and found them to be black and gritty. That completely restored all power and shifting capabilities to normal. Lesson to others make sure filters are changed regularly and get complete service records if available.

these trucks need really clean fuel to run correctly