Converting a 2wd to a 4wd isnt a big deal, assuming you weld.  I have seen quite a few of them and I know two people that have done it with first gens. Wasn't the Macho Taco originally 2wd?  The fab work is mostly the same as a sas, other than that its more or less a bolt on deal. The conversion isnt a bad way to go when building a wheeler and changing/moding lots of stuff anyway. However, if all your going for can be accomplished by just buying a stock 4wd then thats probably the best way to go.