There is no easy way to install an electrical heater that will take the place of the gas flame under the coils on these old units. You might look for a overstock electric/gas unit at the RV salvage places around Elkart, Indiana. They have some cheap prices sometimes. With some of the RV manufacturers going bankrupt, there should be some good auction for these guys to pick things up, if they have the money.
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.