Rear bumper plugs? (pic inside)

I know back in the day I use to go with my cousin to the Mazda dealer and get these but does anyone have a part number for these or know where I can get them. They are the black rubber plugs that cover the cut outs where the bumber goes. Here is a pic.

Did you try Mazda dealer #UB4165851 such as JimEllisMazdaparts.com (#65-851B, or #UB4165851). Not cheap, but apparently available.