833 behind a stout 440?

mbaird said
page 13 of Jamie Passons book on 833sView attachment 1715321899

So the difference is not a literal twist or angle of the gears, just ratio's and the teeth on the input shaft, which is the same for 64-65A, and 75A, and 71-72 HEMI ad (edit) 77 and up OD... sounds interchangeable to me? What am I missing....?

Oh, and input bearing and retainer..