SPL Parts 89-94 Nissan 240SX (S13) PRO Solid Subframe Conversion BushingsSPL Parts PRO Solid Subframe Conversion Bushings (SSB) are designed to allow S14 S15 subframes to be mounted on the S13 chassis or vice versa. Our Solid Bushings prevent the subframe from "bouncing around" under drivetrain torque or suspension load, maintaining optimum suspension geometry and reducing wheel hop. Our slide in shim system allows you to quickly raise or lower the subframe to fine tune the roll center anti squat behavior to your