Either a 7.3 or 6.0 is going to need some work. A truck with a 7.3 will be at the age it will nickle and dime you. Diesel or not, the motor may last but the rest of the truck rots the same. I would walk, no, run from a 6.0 powered truck. Several friends of mine with 6.0 fords as PERSONAL trucks, not plowing, not towing, are thousands and thousands of dollars in repairs into their trucks. Head gaskets, turbos, egr problems. One in particular just swallowed a 7k repair bill.
The best decision I made was to buy a brand new gas pickup. I don't tow anything over 5 to 6k on a regular basis. Once in a while towing 10k is perfectly acceptable. Gas trucks keep getting better and better as diesels are becoming overcomplicated and crippled by emissions. Not to mention the 8k price tag increase, and the extra expense for fuel. If you think you are buying a diesel pickup to save money on fuel you are only kidding yourself. Take a moment to honestly consider how you will be using the truck.