I had an interesting conversation a short time ago with a tech rep from Dove Manufacturing. He refused to say outright that Dove made the rockers sold by Indy, but he did say that he was very familiar with Indy's rockers and that they were definitely made fron 7100 series aluminum alloy. Dove's rockers are made in the USA. Zinc is the primary alloying element in 7000 series aluminum and 7000 series is the strongest and most notch resitant of all aluminum alloys. That said, Ken Lazzeri of Indy heads told me several years ago in a moment of genuine candor that their rockers like all aluminum rockers would eventually break. Usually in the form of a clean break across the bottom. He likened it to the cut of a bandsaw. He went on to say that how long they would last had a lot to do with spring pressures. With modest pressures they could last indefinitely. Based on personal experience I have 55,000 miles on my Indybrocks [ sorry Josh, Indy aluminum TA heads ] and they are still going strong. My pressures are nominal and I shift at 6,200 rpm. Of course after Ken told me that I bought two [ left & right ] spares just in case one breaks on the road. Kind of like carring an umbrella on a cloudy day.