NOS K/H disc brake lower ball joints

Interested, but what makes these different then 67? As our 67 has oem disc as well.
DISC BRAKE ball joints use 9/16 inch bolts to attach to the spindle, throughout all the years 1965, - 1972.
DRUM Brake ball joints use 1/2 inch diameter bolts.
A Drum Brake ball joint can be used, just by drilling out the mount holes to 9/16 inch