As far as I know Tamiya do use Futaba servos, sorry for the confusion.
The original servo saver for the mini is the one I really need to know about, as Saint has mentioned it is the correct length for the mini. I think KO & JR are the same spline as Acoms/Sanwa? 'Cos the servo savers are labelled Acoms/Sanwa and Tamiya/Futaba.