drum to disc O.E issue

From a '73 up with any A Body Brakes....
Just measure the Ball Joint "Nut" size to verify it IS a Large Ball Joint Control Arm.
Measure the Nut from one side across the Grease Zerk to the other side on the flats.
Or the Castle Nut on the Threaded Stud will be larger than the older/small Ball Joints too.
I say this because some of the early '73's still used the older Small Ball Joint Control Arms.

Don't be in too much of a hurry finding them!
I am even broker than you seem to be right now and the prices on BBP Disc Brake parts is out of my financial reach for now.

Later,
Bruce B.