Summary

This is my edit of Austin's design, as my dishwasher rails are slightly different.
My edit more closely resembles W10195622 dishrack rear end stop clips.

I thickened the main rectangle end, cut off the cross piece in the middle, and also trimmed the bottom of the "V" to allow a little play.
On my first attempt, I printed the piece with the flat rectangle at the bottom; however, the installation stress runs in that direction, so part of mine sheared off on the first try. See pic for the direction to print. I recommend adding supports and printing it sideways.

I printed in PC CF because my dishwasher gets too hot for PLA.

I tried to install the rail and then put the clip on, but that proved to be more challenging than my temper would allow. Therefore I installed it first (use a bench vise for nice even pressure to pop the clip in) and then forced the rail sideways between the rollers against the side wall. My rollers are old and had enough play for me to do this.