I have a 7.3 and a 6.0 love them both. The 6.0 tows better but I think that might be cause it is newer. The 7.3 has by far more power but it is no means stock either, and the 6.0 is stock so we will see someday when the 6.0 has some mods done to it.
I've spent some money on her. I've replaced the alternator because the voltage regulator went out and over charged the batteries at a little past the 5yr mark. Also had to replace a gasket on the fuel regulator. Had to put new tires on her at around 90k the originals were nearly worn out. New shocks and steering stabilizer at that time as well. Plus some add ons as well.
I posted on the first page 3 years ago... got my injectors replaced and everything fixed up, and except for a cracked degas tank leaking coolant into the ebp sensor and shorting it out causing a forced idle, the truck has been trouble free.
I have a box of arp's sitting on the shelf, they probably aren't going to get used...it seems they torqued the head bolts tighter or used upgraded bolts or both on the later trucks, because I've never had a gasket problem. And I WORK this truck...15,000 lbs is a normal tow. I have a Edge set on tow, I use it mostly for the gauges.
Son in law has a 06 Dodge with a Cummins, he prefers towing heavy loads with my truck. More torque, better springs (better truck) and he loves the gear grabbing tow/haul mode, and built in brake controller.