the C body [1974- 1978] had larger ball joints than the A,B, & E bodies.
however, the 59-73 C's used the K772 upper ball joints, [same as the A,B, & E] but different lower ball joints. with that said, i "think" [actually, i'm pretty sure] the taper is the same, but the bolt hole to spindle is different, and the steering arm to tierod is a different length and shape than the A, B, & E's.
this is from years of screwing around with disc brake swaps and the moog master catalog i have.
don't know if this helps you or not.