Super six

what rear end gear was in those cars? Were they both the same?
My Dad's was a 2.9x, and it was also an early model year build, having SBP and 4 wheel drums.
It was supposed to have been my 1st car but shortly before I got my license for the 1st time my brother wrecked his 74 Charger and needed a car "right away".... so my brother wound up with it and I was so pissed at my Dad for letting my brother have "my" car..... the few times I got to drive it I loved that car/ even with its manual steering and brakes. I later had a 79 D100 w/a 3 on the tree and manual steer and brakes.....
In between I had had a 76 Charger (the car my Dad had replaced the Duster with for his "work car" for a few years) and I would get so mad when Mom would take my car, to go shopping or blueberry picking, strawberry picking and I had someplace important to go... like work/// and had to "bum" a ride. That 3 on the tree and manual steer truck, cured that problem really quick, she somehow never stole my truck...... when Dad had had his 71 F250 some years earlier I remember riding with her a couple of times uptown to the post office and she never took it out of 2nd gear the whole way........

You mean the Feather Dusters? They were serious highway gears, I would imagine. I don't really know for sure......and I had one. It was an automatic though.