Trying to remove transfer case, both axles out, still jammed and can't be pried off

I'm having the transfer case replaced at a shop that I trust. They're trying to get the old transfer case off. The vehicle was making thumping noises once per wheel rotation when the wheels were turned. Both axles are out, but it won't come off - Is there something else which retains the input shaft to the transfer case? My mechanic has used 2 x 5 foot prybars and it's still not coming off.