creaking sound from 4-lo?

hey guys
i have a 94 4dr rustys 4.5 all that stuff.

i was wheeling today and i put it in 4lo and started hearing this creaking sound like an old door was being opened slowly. it was sparatic and didnt really effect the way it crawled, just sounded terrible.

i have the stock 3.07s on 32s but am regearing asap, (had to wait until the money came....)
could it just be strain on the t-case tryin to turn the rubbers or something else,
thanks guys

I have somewhat of the same problem in my stock 88, I didn't hear the problem until after I replaced my radiator and (obviously) didn't bleed the system correctly, my creaking seems to be air in the system and after I open the resivior cap(stupid closed circuit!) and let the pressure out I don't hear the noise. Mine happens in 4H and 4L though.