I was finally able to find a guy to remove my window in order to take photos. It looks like your 1/2" TOP SASH GUIDE Product Code: 18-036 but you're the experts. Also took a photo of another plastic piece that I could use but do not know its name.
Bob from SWISCO responded:
December 28, 2020
This reminds me more of our 18-166. Look over the dimensions and let me know if this guide matches up.