toolmanmike it's a '64 Dart with a 273 and auto. So judging by the spotter's guide you were kind enough to provide, it appears to be a 7 1/4" rear end. Thanks for that. Any vendor recommendations?
A wanted ad here on the site would be your best bet. Dr. Diff is a great place to buy parts but the 7 1/4 rear isn't the most popular so reproduced parts will be hard to come by.