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As long as you have the steel frame carbureted YFZ450 and not the Aluminum frame fuel injected YFZ450R, which were both available in 09, then any YFZ450 a arms from 04-09 will fit your machine. The YFZ450R a arms are long travel and will not fit. You can also use the a arms from any Raptor 700 from 06-14, as they used the same arms as the YFZ.