Nice truck. I know you will like it, especially pulling a trailer. But I am a little biased. The 03 has 190,000 miles, injectors and pump changed under recall years ago, rebuilt the front diff at 100,000 when a bearing went bad, new water pump at 150,000. The 08 has 100,000 miles. I still have the factory brake pads on the 03. Other than that just regular maintenance.
Diesels need clean air, oil, and fuel. I get an oil change and air filter every 10,000 miles. For me that's twice a year for each truck, runs about $125 at the dealership. Fuel filter every 50,000. A little money up front is well worth it.