1960 Trailer with Hehr Clear View 1009 19 40 ER windows

[dkaliszewski]

I am reposting, I realized I posted in the wrong section:

We have purchased a 1960 Tradewind with three missing window sashes (the piece that holds the glass and moves). The Hehr window part number is: 1009 19 40 ER. We have discovered these are very difficult to find.

Does anyone know if the Hallmark-12 window can be used to replace the whole window? Airstream Supply has reproductions of the Hallmark-12 in a 18 1/4" x 39 1/4".