The Enthuspec solid bushings for the S14 Nissan 240sx allows you to use a S13 rear differential in a S14 Subframe. On an S13 Differential, the front ears are solid mounted from the factory. However the use of a S13 Diff can be used in an S14 when using an S14 rear cover. The OEM Factory bushing used in the subframe is very soft and flexible. The differential moves alot under hard accelerations and driving conditions. These bushings solidly hold the differential to the subframe, eliminating the unwanted movement and help with wheel hop to get the power to the ground. Bushings are CNC machinced aluminum for precision fitment. These are NOT to be used with OEM or Non-solid front S14 diff bushings. The rear cover could possibly crack if the front of the diff has movement from OEM bushings. Designed for racing purposes where noise and vibration is a trade off for performance.