Good luck man. Sucks to be stranded because of a belt you cant get.

Why did it fail? Last time I snapped a belt was in the 4.6, and it was because the alternator seized. Good thing I had it towed because at first I wanted to replace the belt on the side of the road. Didnt see the alternator was seized till the shop was halfway through removing stuff to access the belt area.

I suggest changing everything while you're there. Like the cooling system, parts of the drive belt system like to fail one after the other.