without hearing it i'm just throwing out a piece of info, usually when the carrier bearings are going bad you can either trigger a noise or make it go away when turning as the carrier gets a side load put on it and the bearings shift slightly in the races. if it's not a wheel bearing I would pull the axles out and pop the front diff cover and carrier off and inspect the surface of the bearings and the races for pitting. the gear pattern on the d30 is set by shims behind the bearings to you can do this without fear of messing something up. Just make sure the caps go back on the correct sides facing the same way they came off and torque the bolts to 60 ft lbs
If you decide to tear into it I did a writeup when I replaced the seals on my d30 a couple years ago so you can see what you're getting yourself into.
http://www.naxja.org/forum/showthread.php?t=937821