Fred
If there is enough belt left, you should be able to take it to a farm supply store or auto parts house and they should have a measuring board that will measure the length and width. You might have to hold it together if its broken in half but that should get you pretty close to the right length. One other problem you might have is your belts longer then there measuring board, but its worth a try ,You will have to ask them at the counter to do that for you too