The OEM shifter cables do not move in a true linear fashion. When installing replacement solid brass bushings or roller skate bearings in place of the original bushings the natural twist of the cable as it is going through the range of motion is lost. The natural twist is dealt with on the OEM bushings in the rubber material they use which allows the flex in a non linear way... as it should be.
The advantages of these shifter bushings are:
CRW Standard spherical shifter bushing kit or CRW PTFE lined spherical shifter bushing kit (PTFE lined is a teflon lubricated liner inside the spherical bearing)
CRW spherical shifter bushing kits include: spherical shifter bushings, washers and OEM retaining clips