Pretty positive the lower ball joint is the same and it's only the upperthats different form the early disks to the lbp disks. Never once heard anything about changing a lower ball joint. And never had to change the lower ball joint.
Lower BJ assembly is not the same, 100% sure. lower balljoint to spindle bolt spacing is the same on F/M/J late B and 73-up A. Both are a wider spacing than the 72-back A lower balljoint to spindle bolt spacing, so the 72-back LBJ assembly will not fit. All the LCA's use the same size tapered BJ stud.
