When I installed my diff drop, I ran into the same thing but was able to eventually get them loose. Remember that if/when you do get them loose, apply some anti-sieze when reassembling them just in case you ever need to break them free again.

When I helped CSTYLES install his diff drop, we ended up doing the same thing that LittleBeast did & FUBAR'd the center link. He actually took a torch to the old one after it was replaced to eventually get the joint free (not sure if that part was out of anger or out of curiosity to see if it could be done).

What's happening is that the joints are designed with too shallow of a taper. When the castle nut is installed, it causes the tapered shaft to bind. If they had been designed with a steeper taper we wouldn't be having this trouble. Hind sight is always 20-20.

When using the puller, remove the castle nut & then put it back on upside-down (flush with the top of the shaft). The nut will help to protect the threads & shaft.