My 2 cents here, I've had several 4.7l engines. 2000 Dakota 4x4 5spd, 2000 Grand Cherokee Awd, and my current 2003 Durango Slt Plus Awd. Between those 3 I compiled over 800,000 km. Only engine issues were, 1 water pump, 2ignition coils, 1 tps, 1 exhaust manifold, and a bad rocker arm. That's all. I've also owned 2004 Dakota 4x4 Quad Cab, and 2008 Dakota 4x4 Quad Cab, both with 4.7l.
If they're quiet and smooth when they start and run, there probably pretty good.
As far as issues with the Durango, the ac/heater blower resister block and connector will go bad, matter of time. If you live in a rust belt like me, watch the oil pan, trans pan, and rear hatch for rusting out. Steering shaft will go bad, and if you replace the front end parts with good quality ones as they go bad that no longer is an issue. Front drive shaft has a cv joint at the transfer case end, I replaced that too. All that being said, I love the Durango and will look for another 2002/2003 Slt Plus when I need to replace this one. Like I said just my