As with anything, difficulty is a mushy term.

Anything can be done and the difficulty depends on your present skill level and willingness to learn something new. Then with a little help from your friends, your off

h34r: /emoticons/
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Right off the top of my head, add transfer case, modify or get new rear drive shaft, new front axle with gears to match your rear ones or vice versa, various mods for hookup and function, etc.. Gearing depends on what you want the truck to perform best at plus tire size. You can check the numbers with a little math. Look at Jeff's Bronco Graveyard 80 and above catalog for a neat chart and the formula for selecting gears. The reason is say 80 and above is that I think the chart in the catalog for your year range is messed up, atleast my downloaded copy is

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I sure there must be someone here that has actually done it, and can supply more details. Your local friendly auto recycler would be a good source for the parts, though you probably would need to inspect and rebuild some of it, atleast seals and gaskets Probably with a good Google search you can find an article or two on it.
Sounds like a great project, might as well do a lift while you are at it. Infact you got me a little excited, maybe I'll go out and get me one too. Ruthie would love another project going in the back yard. :-"
GO FOR IT!!!!!
Good luck and let us know how it is progressing.

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