I assume that you are asking about the Kelsey Hayes 4 piston caliper disc brake assembly that is used on the A body cars.
Everything is the same from 1965 to 1972, so i don't have a clue what that parts source is telling you when you are looking up parts.
When i come across calipers that aren't cost effective to rebuild, i just turn them in as cores, as i have a local independant parts store that handles, and can get the Centric line of brake parts.