Snap in Glazing for Milestone 2000

I'm looking for snap in glazing for a window series where the original company went out of business. It was made by Florida Extruders and is Milestone Double Hung Series 2000. Dimensions are about 1/2 square as shown in diagram. I'd rather not replace all four sides on a given window as typically only one of the four sides is cracked.

Have you found this snap-in glazing? I can't find it anywhere and the suggestion from Paul isn't the same size. I have the same problem with yellowed and cracked glazing on almost every window. Can you imagine having to replace every window in the house just because of this?