Old nylon shower door guides

Hello, these guides are on old shower doors from the early 80's. The doors have a flat vertical bottom that would screw into the guides. The guide itself, on one end attached to the flat vertical bottom, and the other side is an oval or oblong and attaches to the tub track by turning the guides flat sides into the track, then turning it downward and screwing the door to the other end of the guide. 2 for each door.