If you have a baby pipe wrench(a six or ten inch pipe wrench), you can try putting a box end wrench over the nut, spin the shaft until the wrench hits something(not something fragile) the trying to turn the shaft with the pipe wrench. Down side is the pipe wrench will eat the threads on the top of the shaft, but if you can spin the nut far enough up to get a small channel lock under it, you can usually force the nut over the remaining threads with a socket/rachet while holding the stud under the nut. 'Not easy, but better then trying to cut the studs off.