1983 f250 2wd to 4x4

I have a 83 6.9 that is currently 2wd that I would like to make a 4x4. The truck currently is on coil springs so I would like to keep it that way when I do the conversion, and I know I can use the 05+ axles but they are hard to come by without being over charged for it. Just wanted to see has anyone else done this conversion and what are my options before i pay a wrecking yard $800. Thanks In advance

I am just curious if you pursued this conversion further?  I recently put a leaf spring Dana 60 kingpin in my '85 2wd.  Not finished, but it's in place.

I'm curious about the logistics of the coil springs and other mounting systems between the two frames.  My perception would be this would take some significant engineering but maybe I am wrong.