Dana 70

The thing you got going for you when looking for a Dana axle is they are not rare. They are so common
If one doesn't have a track lok, power lok or Detroit
locker I won't give them a second glance even at scrap price unless it has a gear with the ratio I wish to use. That's because the limited slip differentials are expensive and without one you pretty much bought a bare housing that you still need to pay to modify. Even if you do the housing fab work yourself
you will need to obtain ends and perches. I cut these parts off 8 3/4 housings myself being cheap.
Best to start with an axle with a slip differential from the start. I like the power lok for a street car.
Of course if you were wanting to use a spool any housing with a usable tube length will do.
Here is a picture of a 60HD compared to a 70 pulled from the net. You can see what kind of extra mass
they can have. The dana 60HD shown has even more mass than the dana 60 that is generally used in cars. A couple things to note about using a Dana in a A body is they can be close to the stock fuel tank particularly when they are relocated reward to make clearance for tires to the front quarter opening. The truck axle tubes are also twice as thick and combined with the extra case weight of the HD60 or 70 adds to the unsprung weight. So when your car absorbs a bump in the road this mass reacts against the body weight of your A body. You dont have the weight of a truck to control this unsprung weight as well when installed in a lightweight duster.
Even if you found a 60 with a power loc it may not have the correct spline side gears for the axles you plan to use. This can add to the cost of doing a truck conversion also.
I am not posting this to discourage you. The opposite infact. I have built many truck Dana's and they can be very economical and strong both.
It does help to know how to pick an axle for your starting point to help keep cost down. I may look under 10 trucks in a yard before I find a decent start.
The last time I went I found four and got them for 75.
each. I cut the floater ends off with a torch and dropped off the axles and brakes before putting them in my truck. I jacked up a lot of trucks to find the ones that could be built on the cheap.

D70vsD60.JPG