1964 Barracuda video Back Glass breaking!

I was talking to Nigel (Mills) up at National Moparts on the weekend . I was up there looking for interior stuff with my friend mikes270Dart. They are restoring a 66 Barracuda so this topic came up about the rear glass. Nigel told me he dropped a sledge hammer on one by accident and it did not brake,,I believe him , they are almost indestructible.