First thing just to MAKE SURE, is to pull one of the axles and physically look at the splines to make sure they look similar to the 8 3/4..If so being a 3/4 ton rear, it is so simple, it should be illeagal...The onlky thing you really gain in strength IMO is the center section though...All I wanted was the braggin' rights that I had a Dana 60 under my junk so I did it.
All you need to do is cut off the truck ends of the Dana and and old 8 3/4, measure three times, then reweld to the proper length you need to fit under whatever car you chose, then slide in the 8 3/4 axles, Brake backing plates, and drums from the 8 3/4 rear..
only drawback to this is the fact that there is NO PROVISION for a pinion snubber on the Dana 60 "truck" rear. You will have to custom fab one as I did usuing the old 8 3/4 unit. it isn't all that hard. Installing a rear quarter panel is harder IMO.....Good luck..See some of my threads on here for pics of my custom pinionm snubber.