Rob & Shari,
Sorry, I may not understand your question.
Do you mean thickness of the panels?
All the panels are year specific. I actually called AIRSTREAM, to get the part numbers for my year. They gave me the wrong part number for the big upper panel (307" long). Master Andy from InlandRV saved my day, catching their mistake. The panel they told me to get would have been some 4" too short (the heights, not width).
The thickness of the material is .040"
It comes precoated from the factory (new alcoa coating technique) and has a protective film, which saves you during installation.
It matches the old original panels from 1979 rather well.
I hope this answers some of your questions.