‘73 Duster Rear End Options!
So in 73 and 74 the 340-360 Dusters (most of them) came with the 8 1/4 suregrip rear end. Usually 3.21 or optional 3.55 gears, and they are big bolt pattern. They are strong and the 8 3/4 has a reputation for strength also, but most A-body 8 3/4 units are small bolt pattern. You could get either and have them beefed up a little. Nice Duster!