73 Dodge Dart Sport

I can't find, for the life of me, where to buy the nylon guides that hold the side windows to the track when you roll down the window. It's a Rectangular nylon piece with a hole in the middle where the ball goes into it. I've searched many sites to find nothing. Any help would be great, or if anybody can pull them off a parts car. I'm sure there are many universal fitting from other cars, but I don't know how to reference this.

Thank you