8 3\4 in a 1975 dart sport ?

any abody 8 3/4 will fit but since yours is a 75 you will need one with big bolt pattern axles i think that is probably what your 8 1/4 would be. the 72 and older factory 8 3/4 for the a body were the small bolt pattern setups so if you get one of those you would have to change axles.