These housing ends are CNC machined from alloy billet steel. They are for street use only and have OEM style inner-axle seals for oil control. Two inches wide with a 3.150" diameter axle bearing bore . The bolt pattern is 3.375" center-to-center across the top and, 2.625" center-to-center vertically. The bolt holes are 3/8" diameter. Designed to use the Ford style axle bearing with the large GM drum brakes. The drum-brake-backing-plate center hole will need to be enlarged to fit over the 3.150" diameter bearing during assembly. Kit contains a pair of housing ends.