In 1967 and 1968, all chrome lug nuts, except A-bodies, were part numbers 2823848 (right) and 2823849 (left), for the Class 2 styled wheels (five-spoke). A-bodies used a smaller 7/16"-20 thread. The other body lines used a 1/2"-20 thread.
In 1969, all 1/2"-20 chrome lug nuts were part numbers...