Ball joints

Yes, lower ball joints are different on your car between drum brakes, and disc brakes.
Drum brake ball joints attach to the spindle with 1/2 inch diameter bolts.
Disc brake ball joints attach to the spindle with 9 1/6 inch bolts.
So the only thing different between disc, and drum, brake lower ball joints is the diameter of the mounting bolt holes drilled in the ball joints.
Hope that helps you out.