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From your screen name (and the 10.25" axle tag) I assume you have an F-250 which, as Bill listed, wouldn't have a 9". Also as Bill listed, no trucks would have ha an 8". But an 8.8" on the other hand is what replaced the 9". See Bill's post for when the 9" was used in the F-150 and Bronco. After that (at least up to 1996) they used the 8.8". (I don't know or really care what Ford used in half ton trucks after that).