Old belts that fail from high mileage tend to snap in two. If your timing belt has stripped teeth, you should check the camshaft for free rotation. In my experience stripped teeth indicate the camshaft is beginning to seize in it's bearings - due to a blockage within the oil passage in the head gasket.
Start the repair and when the belt is off, spin the cam with a socket and 3/8 ratchet. The cam should "back-up" every now and then as the lobes move across the shims. If it simply turns in one direction, and with substantial effort, then pull the cam out and check the bearings. You may also find that the cylinder head is relatively "dry", and has little oil left in the pockets around the lifters.
If it spins freely, and the head is very wet, then just replace the belt. Check the tensioner as well.