I asked this a couple of months ago. I found some good deals on duallys but didn't want a dually. Seems like, if I remember, you had to get a Dana 80 from a 3/4 ton (wider) and also the spindals for the front wheels (narrower). Plus remove the fenders from the bed and have some body work done to cover up all the holes. OR maybe you had to replace the whole bed. Nobody ever said how much it would cost. Guess it depends what salvage yards have and how much they want. But it could be done with those axle changes.