First I would like to say that I am glad to see that you have this identification system for folks to use.
I have Thermal Gard windows that are a double hung model. I have no idea what year they were manufactured nor do I know the model. All I have been able to find is the name Thermal Gard on the locking mechanism cover.
According to your website, the shoe seems to match the model number
15-048. The appearance and measurements match. I am hoping these shoes are correct. The previous owner may have replaced these at some time because there are notches already cut out of the channels for shoe removal/replacement.
Thank you for any assistance that you can provide me.