i have never seen a 360 belt break but i have seen them jump teeth when they are old the hydraulic tensioner stretches the belt even if the car has low miles.if the book says 3 years i would change it at 3 years.the belt service is a lot cheaper than a valve job.you can do it through the access hole without removing the engine.I think ferrari of O.C only charged me @1900 to do the belts on my stradale last year.i only have 3500 miles on my car since the last belt service and the tensioner was out of adjustment.
