You can make a dually front or rear end a single wheel front or rear end by using the single wheel hubs and rotors on the front or the single wheel hubs and drums on the rear. When switching from a dually to single wheel on the rear I think it works out better and easier to put disks on instead of the drums. The axle housings are almost exactly the same only two differences that I know of: 1 spring perch width on all 1 tons was different that 1/2 and 3/4 tons. 2 I think that the break backing plates are in different locations fro dually to single wheel.
The fronts are real easy. The rears do require quite a bit of work to make them mount to any thing but a 1 ton frame.