Not sure of the light style but the rectangular ones from the '70s are available new for less than $20 each. Also if the shades are yellowed you can use "daylight" LED bulbs and the lights will have a nice white glow.
This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.