They should swap in exactly the same since there were no differences in engines from 2wd and 4wd. Oil pan configuration would be the only difference. Have you cnosidered tossing the transfer case along with the current engine and transmission? You'll have less parasitic HP loss with it gone plus you'll save another 100 lbs of weight you have to take with you everywhere you go. That should improve your 60' times and fuel mileage.