Peggy, on the 1970 S small date, the 9 curls all the way around, the point of the 9 is sharp, and LIBERTY is weakly struck. On the large date, the 9 does not curl around, the point of the 9 is blunt and LIBERTY is a better strike.
Oh crap, now I guess I have a new search to do in my 1970-S BU rolls. Thanks a lot. Is the zero the best diagnostic? And does NGC slab that variety?