R154's have always been notchy. They are derived from a truck transmission. I rebuilt mine with a drift motion kit and it improved the downshifting into 2nd going around a corner but the notchyness was still there. The C's kit requires that the 2 half-moon pieces go down into the transmission housing first. The round housing goes on top with the green Toyota shifting bushing inside. That puts the shifter tip in the middle of the shifter arm where the stock one originally sat. Any other set up will cause trouble.Ya that’s what I have( the c’s) in my car. I think it makes the shifting notchy. I tried it with the shaft removed and a knob with set screws directly to the shaft, nice low height but awful shifting.