pontiac and chevy disc spindles are slightly different but should be interchangeable. The lower bolt holes for the steering arm on one are larger than the other but are otherwise the same as far as i know.
the caliper mounting bracket was the same part # for both spindles 69 f,x,a 70-72 x,a,g 72-74 x.
the spindles were the same part on the pontiac 67-69f, 70-72a/g the rest took the chevy spindles.
the 67-69 firebird and camaro used the same ball joints.
