4x4 conversion

i've got a 2wd 1990 ranger that has everything else i want, including some parts i custom made for it that won't be transferable, so i want to make it 4x4. i've got the 5spd and a 2.9 (which will probably be replaced by a 4.0 when it goes). does anyone have any experience or now how on this? i know that it will be a large time investment, but to me it is worth it, plus it'll be fun... anything will help. does anyone know of a kit like the wolverine kit for the earlier rangers..(i think not??)