[Bill Cilker]

The part you need is called a Dove Tail Guide insert. They are used on the Victorias, Slant windshield sedans and and I would assume 400As & 68Cs. Bratton's says that they are used on Slant Windshield cars. Bratton's part number is 30970 on page 135 of their 2018 catalog. $6.75 for 2.

To remove the insert, push it toward the interior of the car and then pull up(bottom) or down (top) on the outside edge.