Quick ratio factory boxes were available for awhile, those were 16:1. But those weren't offered as an option for '71 A-bodies.
24:1 works out to 5.3 turns lock to lock (per the factory manual)
20:1 is 4.5 turns lock to lock (mopar performance made replacement 20:1 gears for awhile)
16:1 is 3.5 turns lock to lock
