I need some technical info on a B-body disc brake swap

A friend of mine bought a disc brake set up off a E-body? to switch his 66 Coronet toDisc brakes. He ran into a problem on the lower Ball Joints. He ordered new BJ's but the bolt holes on the lower BJ's are further apart than on the new BJ's. Any idea what spindles he has? Or what BJ's he needs to buy?