Jeep's JK Wrangler utilizes two different sized rear Panhard rod bushings across the production range. One with a 39.1mm O.D. which is the SPF3658K kit here. There is also a 39.7mm O.D. bushing kit which is our SPF3913K. If you choose to purchase the complete vehicle bushing upgrade kit, KIT173K, both versions are included. Panhard rod bushings form the vital pivot and link between in the steering and suspension system. Worn bushings allow significant deflection and movement leading to slower responses, a sloppy drive, irregular and excessive tire wear and diminish every facet of the way your vehicle drives “ while contributing to driver frustration and fatigue. The wear is accelerated and the impact of worn bushings is even greater in upgraded trucks and SUVs where the higher weight and impact of items like larger wheels and tires all work the bushings harder. SuperPro's polyurethane bushings are the culmination of nearly 5 decades of suspension expertise and development in Australia's harshest terrain. Designed with durability as a paramount feature we also bring ride and passenger comfort to the forefront of our development. Your vehicle should treat you as well on the way to and from the trail as it performs on your adventure. Our designs and material compositions retain OEM levels of noise and harshness isolation while delivering superior performance and road manners in all conditions.