Hi Molly -- Welcome to the Forums!
Too bad about your hinge. You'll probably need to troll around Airstream groups a while before you find the right item. I would suggest posting a digital photo in a wanted ad because some parts were used during several years' production and on more than one size Airstream. There are free classifieds here and at the Vintage Airstream Club
. Perhaps the classifieds at Airstream.com? Cast your net as wide as you can. You could also try contacting Colaws RV Salvage
in Carthage, MO. Good luck in your search!