Jeep's JK Wrangler utilizes two different sized front Panhard rod bushings across the production range. One with a 36.5mm O.D. on one end and 39.7mm on the other which is the SPF3912K kit here. This size is used on vehicles produced from June of 2008 onward. The other uses a 38.8mm O.D. on one end and a 35.8mm O.D. on the other ;this uses ourSPF3912K kit. This size is found on early builds produced through June of 2008. 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.