HELP!!!!74 4 door cornet disc brakes

you cant use the UCA from anything but an A body on another A body. You CAN however use those spindles, dust shields, caliper brackets and calipers with a 73 and up A body UCA, or Dr Diff's ball joint adapter on a 72 or older UCA, and 73 up A body lower ball joint on any 66 or 67 up A body.
Same brakes/spindles (more or less) on all F,M,J and 73+ B bodies.