Thanks for writing in! There is a chance that we can supply you with replacements for the top guide you are searching for however, it would be difficult to determine exactly which one you need without seeing it removed from the door.
There are many different versions of the guide you are searching for and we only sell four of them.
Start with carefully comparing your existing hardware to our 86-010, 86-025, 86-026 and 86-028. See which one of these might be the replacement you are searching for.
The dimensions for each of these parts can be found on each of the product pages on our website. You may access them using the links above or the ones below this thread.
Please feel free to reach out with any questions you may have.