It may have the wrong spindles or the wrong bearings. If the bearings are loose on the spindle the car will move all over the place.
Fun fact, 70-72 B/E bodies use spindles that look just like 73+ disk spindles. But they use a smaller inner wheel bearing. Those spindles with 73+ rotors and wheel bearings can cause the “not tightening” issue with the spindle nut. But a washer can’t make up for the inner bearing being too big for the spindle.
