Just another k.h. Swap thread.

If you do some searching you'll find parts are interchangeable. For example Rock Auto lists different rotor choices for disc brakes on a 69 Dart, yet the "out of stock" rotors are the same part number as the 66 Dart option. Then a 69 Barracuda has even more rotor choices and again the "out of stock" rotor is the same part number as the 66 Dart option.
Therefore the 69 Barracuda rotors are the same as the 66 Dart yet the 66 Dart only gives you one rotor choice, whereas the 69 Barracuda gives you other rotor choices. Have a look.