SPL 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 preference. Raising the subframe will compensate roll center for a lowered car at the expense of increasing anti-squat. Lowering the subframe will decrease anti-squat at the expense of roll center. This is NOT Formula Drift legal! Subframe swaps are not currently legal under FD regulations.SPL Parts PRO series Bushings are precision CNC machined from 6061-T6 Billet Aluminum for excellent fit. Our bushing kit also includes optional rubber isolation washers to reduce noise transfer from the subframe to the chassis. Sold as complete kit for one car.Made in the USA. Applications: 1989-1994 Nissan 240SX (S13) Installation Instructions: SPL Solid Subframe Conversion Bushings