[Bob Bowman 1968]

I am working on a 1967 Firebird that has a 326 in it. We are adding a four speed automatic transmission. The rear end in it is an open 2.56 which is too high for fourth gear. The rear end is stamped XB. It has the mono leaf spring perches and factory traction bars. 8.2 rear end. We are looking for a posi unit that we could use 3.73 gears with. Does Auburn, Eaton, or Dana make a posi carrier that will fit into the original rear end housing? We have been told that the housing will not work with lower gear sets. The car is not going to be raced. Going to run street tires and do a burn out one in awhile. Not worried about the strength of the 8.2 since it's going to be a street car and not drag raced. Any advice or thoughts?