On the S14, the rear differential carrier is supported with rubber bushings. As they wear out and become soft, your drive train tends to shift and move. This could lead to parts breaking or coming loose over time. It is recommended to replace the worn out rubber bushings with stiffer polyurethane bushings to keep the drivetrain from moving. If you don't mind some noise, STANCE solid aluminum rear diff bushings are perfect for keeping the diff carrier in place!