Sliding guides, plastic inserts

Thanks for posting. Many PGT windows have used the 67-028 Face Guide, but I am not certain this is what you need. Take a look at this guide, as well as the others I have listed on this page, and let me know if you think one of these matches what you need.

There is unfortunately not any guide that matches that description, no. I've honestly never seen such a thing.

I'm also not sure yours is designed that way either. I can see a bit of the extension going under the lip of your window. You may want to remove your original to verify.