Plastic window clips at bottom rail of window

Hi. Would like to know what these are called and if you carry these replacement parts. They are located at the bottom sides of the"lift rail" on the interior of a non-tilting window. They broke off when the balance broke and the window came crashing down. If you need specific dimensions , let me know. There are no stamping or markings on these parts to identify manufacturer. They are specific to right and left sides. There is a lip that is broken off directly vertical to the L and R stamping. Any help would be most appreciated. Thank you!