are you sure your quick disconnect works or your warn locking hubs are engaged? - just saying...
if your tires are worn evenly (or new), same pressure and you're not loaded in the rear its fine as long as you drive straight. once you start taking turns you'll break something. You can test this easily, go in your preferred mall/walmart/etc parking lot, shift in 4wd and start driving circles slowly, if it stops don't give up - try in 4Lo and keep at it - then report back how many 360s you did before you start hearing funny noises
for the rest of you reading this keep in mind Dave's Jeep is special, so don't try this with yours (just so i don't get blamed for the damage).