Part #: KSB751. Upgrade your Subaru's driving experience with the Whiteline rear differential support lock kit. This budget - friendly yet effective bushing kit is designed for 2002 - 2007 WRX and 2004 - 2007 STI models. Stock rear ends on these Subarus often have issues like excessive play, slop, and the well - known 1 - 2 upshift 'clunk' because of soft OE rubber bushings. By replacing the weak stock parts with Whiteline's high - performance polyurethane, you can lock the rear end firmly. This results in better rigidity, improved input control, and gets rid of rear driveline slop. Get top - notch performance at an affordable price from Whiteline. Part Number: KSB751

Using the Whiteline rear differential lock kit is a straightforward process. First, make sure your vehicle is parked on a flat and stable surface, and the engine is turned off. Then, locate the rear differential area. Remove the old, stock bushings carefully. You may need some basic tools like wrenches. Once the old bushings are out, install the Whiteline polyurethane bushings in their place. Ensure they fit snugly. When it comes to maintenance, it's a good idea to check the bushings every few months for any signs of wear or damage. If you notice any cracks or excessive wear, it might be time to replace them. Also, keep the area around the bushings clean to prevent dirt and debris from causing premature wear. And always follow the standard safety procedures when working on your vehicle, like wearing protective gloves and eyewear.