Lisa,
What you are looking at is a Kaiser-Frazer accessory item originally offered for fixes on 1947-48 Kaiser and Frazer cars. Later, 1949-50 models were added. They never made a kit covering 1951 and later Kaisers or the Henry J. They came for the left or right sides.
They still show up occasionally at KFOCI events for sale but I haven't priced the item in a long time. I got one of the kits years ago; it's still down in the house at Cave City.