75+ 4-speed FJ40/55 t-cases have a 1.999:1 low ratio, 16 (or is it 19?)-spline input gear.
73- 3-speed FJ40/55 t-cases have a 2.313:1 low ratio. 10-spline input gear.
'74 is a morph year...they swapped to the 4-speed tranny but still have 3-speed cases laying around, so the early production...