My tranny of choice would be a 4l60e and an nvg242 transfer case with a driver's side drop. I'd use an Art Carr cable shifter or mod the stock one. This eliminates the bellhousing match problem and the ratios in the 4L60E are quite like the KM 148, so you won't be running 4krpms at 70 like the 3spd a/t you propose. Of course, you could change the diff ratios, but you have to change both, of course. Much higher cost and fab work. The 4L60E has a .7 o/d ratio, and the nvg242 will allow operation just like selectrac, i.e., 4hi2wd, 4hi4wd unlocked center diff, 4wdhi locked, 4wdlo locked, and is quite stout, and can use many of the mods available for the nvg231 like doublers and very low ratios in 4lo.