Ford: 4x4 noises, ford bronco ii, ford bronco

Question
" I have a 1990 Ford Bronco II with an electronic 4x4 shift and auto locking hubs. The other day I engaged the 4x4 (not on the fly) and my vehicle started pulling hard to the right in both high and low. I do know that my shift motor is engaging. I try to engage the 4x4 once a month to keep this working. I had not done this for the last 2 months.  After disengaging and unlocking the hubs and in 2 hi my vehicle seemed ok (no pulling). I tried to swap the hubs R to L and L to R. When I engaged 4 HI it appeared ok, but when I went to low it again pulled hard right. Now both in low and again in hi. I disengaged the 4x and drove backwards to unlock the hubs. It was now pulling hard left in reverse and was making a loud noise during movment. I then went forward and my vehicle appeared to be ok again with no pulling in 2 hi nor any noise. Just tonight I was trying to remove my front driveshaft for transmission removal. The driveshaft was free for two turns then decided to lock in place. I am confused by this and if you can shed any light on this it would be helpful.

I had asked this question of another expert and was told that a needle bearing was bad in the right hub.  I have just taken apart both of the hubs completely and both bearing are good.  The U-joints in the front axle are also good.  I regreased all the bearings and reassembled the hubs.  I tried my 4x and 4 hi appears to work ok but when I go into 4 low I hear a grinding noise.   When I unlock the hubs everything appears fine.  I also checked the front differential and the oil level is ok.

Answer
Bookrat, what you need to do first is remove the front diff cover. and inspect the spider gears for cracks, also when removing the cover check to see if any metal is laying in the bottom. turn the ring n pinion and check for chips or cracks. do this first and then let me know.