The 2WD and 4WD AW-4s have different main shafts. It's not just a matter of putting the Xfr case adapter in place of the tail shaft housing. Changing the main shaft requires a complete tear down of the trans. It can be done, but it's not really cost-effective. Probably cheaper to get a decent JY 4WD trans.
"Never attribute to malice that which can be adequately explained by stupidity, but don't rule out malice."
My other car is also a Jeep,.. and so is the other one,.. and that one too. How many do you own before it's "a herd" ?