I know I am aging myself, but back in 1957 when my parents bought their new 57 Savoy, after about 6 months we had one break. Since mom worked at the dealer we found out that they had defective ones that the metal was not up to specs. This was corrected and you didn't hear of them breaking until the Aspen/Volare days which I can attest too as I used to have the broken one under my house and I didn't move it so wonder if it is still there since I moved 10 years ago! Ha! Metal is metal and will have a stress point at some time, but when that will be is dependent on amount of stress and number of movements and each one is probably different. We have spares just in case!