Sometimes needle bearins can be tricky. They get a little bit of warpage and the needles can bind in the cage. Or, you can shock it so hard, the needles start to pop out. Did you try spraying it with lube and try to rotate? See if you can get something that fits inside the bearing when you drive it in. That will help to hold the needles in place. I did a rear diff rebuild on a timberwolf a couple years ago, and had something similar happen to me.