Product review (3 stars): Fits a Kitchenaid KUDC10IXWH1
I have a Kitchenaid KUDC10IXWH1.  The rinse aid cap mysteriously disappeared.  I wondered if it could have fallen off and been melted on the coil.  That seemed very unlikely but having read the other reviews, I believe that is what must have happened.

I found several suppliers online that had the part and wanted to charge a ridiculous amount for it.  I found it here for a somewhat less ridiculous amount.  It fits fine.

It's going to be overpriced wherever you buy it so if you want one, this is probably the best place to get it.