Changing belt - how often?

So, how often one must change the belt (the main one, dunno what its called) for turbo diesel engine?
Dealer said every 90k kms (60k mi) sounds a bit too much, m?

Primera P11,'98, 2.0TD

All timing belts on primera diesels are 54,000 miles. you will find that you have 2 belts. 1 cambelt (drives engine) and 1 pump belt (drives diesel pump.