Originally Posted by Cab_Burge
All three of the modern, made after 1962, third members came with the course spline pinion gears and both size U joints.
Some of the 1969 and later third members came with the fine spline pinion gears also shruggy
As already pointed out the carriers, 741,742 and the later 489 cases all have specific pinion gear diameter and specific bearing race sizes so the gears will not interchange between them shruggy


What Cab said, the factory put them all out in both sizes.