Product review (2 stars): Better, less expensive solution
While this is certainly the replacement part for your KitchenAid dishwasher, I read the reviews and realized that a more permanent fix was necessary. The plastic prongs that secure the wheels will continue to break, due to the high heat of the drying cycle. The solution recommended by huemanOne is easily accomplished with a little leg work and minimal repair skills. His video is posted on YouTube - "KitchenAid 10350376 Rack Adjuster Fix". I used a Dremel tool to remove the prongs that hold the wheel and clean the remaining plastic.  While most parts were found at my local Ace Hardware, the 9/16" outside diameter washers, (the part that was most difficult to find) were found at Lowe's, in the plumbing section (pack of 10 for 1.99, manufactured by Danco, package says 1/4 Flat Washers but below that is 9/16" O.D). Just remember to cut the excess screw length with the Dremel tool flush with the lock nut to allow it to fit in the tracks. Keep in mind that there is no harm in trying this solution since the part would be discarded anyway.