The Mustang guys have put up some very usefull history and info on the Ford 9in. Look up kevinstang and ultrastang 9 inch. They answer a lot of the questions about the different 9 in and how to ID them. Interesting the 1960 Bird had the big bearing rear end. The easy way to identify the bearing size is by the size of the bolts holding the axle retainer.
NCbird on the Coast of NC
"Dads Bird" for my father