shower door guide

I can't find this item anywhere and really would appreciate for your insight
The picture is from a shower door bottom area - and shows a deteriorated plastic or nylon guide. There are many similar ones on the market but none fit.
The doors are 5/8" thick each and each track (for each door) is 3/4"
The length of the guide is 3"
So the overall dimensions are 1.5"x1/2"(height)x3"
Most guides are for glass doors, not framed shower doors and have a guide width less than this door.
Thanks for any help!