The rear-linkage, just like swing-arm pivot, is prone to wear, not just from use but from road debris and particulates getting into the mechanism. A worn linkage will affect the handling and safety of the machine, so if you are feeling that the rear end is not as tied down as it once was, then an overhaul of the linkage components may be called for.
Listed below are other related parts, including new fasteners that may not be essential to renew, but add so much to the appearance if they are!
Add as many items as you wish to the same shopping cart, a new sleeve 420361258, bearings 920461272 and seals 920491223 for example, and still only pay the same single fixed price shipping cost. This part may have other applications in the Kawasaki model range - ensure the part-number/s you order are correct for your model?