Dana 60 in a Duster:

Get your wheels and tires you plan to run before having the rear cut.

This way you can have the rear cut to the proper size and not have to mess around with spacers or worse, buying wheels with a different offset.

Buy a better spring perch than the MP's.
Box the perch to the axle as well, especially if you plan on running the car hard, using cal-tracs.

If the rear has a track-lock posi in it, it won't likely last long with any decent HP applied to it. Spool it or look for a power-lock carrier.

Yeah they look good...