I don't know about RV dealers, but the end that plugs into the Airstream is a standard NEMA L5-30. This plug will not have the locking ring but is the correct connector. I just brought one at an electric supply house and put it on the end of a standard extension cord to plug into my generator so I don't have to get out the heavy Airstream cord to use it. If you are near a good electrical supply you might try that.
"When you find yourself in a hole - quit digging!"
2012 1/2 Eddie Bauer, Dodge 3500 SWB 4x4 6.7L Cummins 6 spd manual