Well this was about 69 or 70 and I didn't ask the owner if it was original but it even still had the factory hub caps on it. I think it would have been all stock.
Mopar never put a 8 3/4 behind a 440 4-speed car. A-body Dana didn’t exist in 1969 as a new assembly. Also needs a special driveshaft they would not have on the assembly line. And other parts would have to be created and calibrated for 4 speed.
There’s much more involved then one axle assembly for a factory install.
