The FS5C71B overdrive "race" transmission was available as a close ratio (32010-N3130) and wide ratio (32010-N3030). These units are generally not worth as much as the F5C71B direct drive drive "Option" boxes.
It would help to know which transmission you have. Gearing is as follows:
Close - 2.906, 1.902, 1.308, 1.00, .864
Wide - 3.321, 2.077, 1.308, 1.00, .864