8 3/4 Donor

Hey all. I need an 8 3/4 rear for a 1970 Dart Swinger that currently has a 318/904/7 1/4. Been having trouble finding an A-Body 8 3/4 that is not across the country. My question is what options do I have? What are some donor vehicles that I can keep an eye out for? And can B/E body 8 3/4's be modified to fit? If so, does anyone know where? I am in South Jersey. Any help would be greatly appreciated. Thanks.