I suspect the original glass was manufactured by guardian Industries. see the link.

Option would be:
1)call their representative closest to you and explain the situation and ask for some guidance.
2) look up "Glass" in your local yellow pages and call someone for direction
3)remove the door and take to a local glass place and see if they can get you a replacement.

hope this helps

Here is a link that might be useful: Guardian Industries

Many of the sliding glass door lites are the same size. Contact a glass and glazing contractor near you and they will come out and measure it. There is a good chance that they will have it in stock because so many door brands use the same size. Or you could remove it and take it to their shop (as sdello suggested) if you want to save a service call

Hi achiel142,

How's your sliding door? Have you replaced it? How did it go?