After 215,000 miles, I just donated my 2003 Durango. The 4.7L had either a cracked head or blown head gasket. It was blowing antifreeze out the exhaust. The best advice for longevity is NEVER allow it to overheat, not even a little bit. Mine happened on a freeway in stop and go traffic and I was not able to get off the road quickly.
Oil changes are a given but paying attention to the cooling system is the key to keeping them alive.
Craig

Kind of a side note. When the engines overheat and drop the valve seats, it usually breaks the piston. That hot debris ends up getting blown back into the plastic intake, melts into the plastic, and is pretty much impossible to get all the debris out. If you don't install a NEW intake, the debris usually works loose and trashes the new engine. For this reason, most of the engine re-man companies will not warranty their re-mans without the purchase of a new intake.