Product review (5 stars): New and Much Improved Whirlpool Part
I bought this adjuster kit from Results International, so I cannot speak for buying the kit from other merchants.  The kit arrived within 4 business days in excellent condition.  It was contained within a factory sealed Whirlpool box, and that box was packaged within another box that was well padded with air bags.

As I said, this kit from Results International is made up of genuine Whirlpool factory parts (Whirlpool kit part# W10712394).  While following the included instructions, the parts fit together perfectly, and once they were installed on the upper rack of my Kenmore Elite dishwasher, they vastly improved the stability and performance of the upper rack.  The functionality of the upper rack is now far better than when the dishwasher was new.  The original all-plastic parts that came with the dishwasher were very wobbly and the wheels kept breaking off.  This new adjuster kit uses sturdy metal for the main support pieces, and a much superior design for the four wheels.  I expect many years of use out of this new adjuster, but if I have any problems with it in the future, I'll be sure to update this post.