Both the 2.3 and 2.8 engines use a cam belt. I would suggest replacing the belt, pulley, tensioner and water pump every five years of 60,000 miles (whichever comes first).

If the belt fails it will most likely wreck the engine. And I've heard some harrowing reports of engine loss on the Ducato camper due to the belt being run beyond five years/60,000 miles.