Original Rear end type on my 70 Duster

Is there a way to further decipher my fender tag to find out what rear end my VL29G0B Duster came with originally? It shows a D31: Light Duty 904 mated to an E44: 318 2 bbl. There are no codes that I've seen on the fender tag that denotes rear end type. So my guess is that it had a 8 1/4 rear end from the factory, is that an accurate ASSumption :D on my part? It currently has a 741 case 8 3/4 in it, but I'm pretty sure it's not original. Like the rest of the current engine/drivetrain.