I can't provide a picture without standing on my head since the door is still in place. It is a Larson door and the only ID I found on the door was this number.
31490432E 151151028. The channel appears to be about 35 inches to the best I could measure it.
I'm sorry to say that I can't make out what you have from these photos. Would it be possible for you to remove a sample and show us a clear picture of its end profile? Knowing its dimensions would also be a big help. The video below will go into more detail.
