At 400+hp, What kills A904s?

Just had this conversation with a friend. He races stock class and between him and his sons they have 6 cars.
All are 904's. All have hundreds of runs. Cars range is between 12 seconds to mid 9's. In 20+ seasons of racing only 1 broken tail shaft housing. He also told me a racing buddy of his has a 66 Coronet Hemi in A stock. He runs a 904.
Your chances of having failure are slim to none.Now the 904 had to be well built, nothing fancy but correctly done.
When I raced the only failure I had transmission wise was a converter stator that went bad.My 904 lasted 20 seasons for me and the new car's owner has had it for 9 years now still racing it. The car was low HP at around 280 at the rear wheels.Fear not.