Now, don't hold me to this and take it with a grain of salt as my memory is quite shallow on this. But, seems if I recall correctly, someone told me one time they got in there (since going to replace the grain pan anyways) and somehow took the welder and tacked each bolt head to the pan so they could air wrench them off like your talking. Don't ask me how they got up there. Been awhile since I worked in deep detail on pop's masseys and like I said......I just can't remember clearly but this might be something worth pondering. HTH's