Surprisingly, there is no timing belt replacement interval specified for the 7AFE engine (if that is what the O.P. has) unless you are in the severe service category. But most people who think they are not in the severe service category actually are.
I can confirm that the belt breaking on the 7AFE does not have to be a catastrophic event that ruins the engine. But I did have to wait nearly two hours for the darn tow truck to retrieve me at 1 a.m. I shoulda walked home and waited from there, it was only about a mile away so I was pretty lucky.