One of the things you will find out about vintage Airstream's is that little is exact. The older the model the more this is true. Recently a model showed up that no one even knew existed - even the folks here who are much wiser about Airstream's than I'll ever be. That's part of what makes this so much fun...
Here's yet another example of that. This is a
1960. Notice the 13 panel end cap.... Airstream quit making the 13 panel cap in
1957. Good luck with your Airstream...