Re: duallies vs. singles
The front axle has a different hub assembly. If you have a dana 60 front I have a set of dually hubs that I would trade you if you picked up the shipping. The difference is that the dually front hub sticks out alot further to allow it to run bud wheels.
As for the rear, the hubs are also different, dually hubs are like $350 a piece. You can probably find them in a junk yard cheaper. You can also buy aftermarket spaces to convert to duals. Or you might find a complete dually rear cheaper than converting yours.
76ScoutIITraveler,345,727,lockright front,welded rear, 33"TSLs, full cage, custom rust & body damage