Please post a pic or your tail light assembly. If you have the pot metal housing with round lights like they used in the 70's, then you need to remove the three screws that hold the lens to the can, and inside the can you will see a couple of pop rivets that hold the can in the housing. Drill these out and the can should come right out.
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.