Why aren't 998 and 999's more popular?

904 is /6 trans with 3 cluthes in forward and rear drum
998 is 318 trans with 4 clutches in forward drum and rear drum
999 is 360 trans with 5 clutches in forward and 4 in rear drum

gear ratios are interchangeable as a unit...

lockup has nothing to do with drivetrain and gears....lockup is in the converter and valve body...and input shaft...