The Peterbilt Retro Kit Replacement Flex is a practical and efficient solution for replacing the flex in the Peterbilt Retro Kit(PRK-6). With a 6-inch size, it fits perfectly in Peterbilt 359 and 379 makes and models. This flex replacement offers a 5-inch I.D to 6-inch I.D, ensuring a secure fit. Sold individually, this product is designed to provide the necessary functionality and durability for your Peterbilt truck. Upgrade your vehicle with this reliable and convenient flex replacement.