the swingarm bolt gets rust and corrosion welded to the axle .spray with penetrating oil alot and soak it regularly for a day or so . Screw the nut back on backwards and leave a gap for the bolt to get moving .try hitting it with a rubber or brass hammer, after it starts to move unscrew the nut a little but don't go too far and ruin the threads.try hitting it with a rubber or brass hammer, next I try a block of wood against the backwards nut an whack at it,If it's real stubborn Get a large drift or center punch in the center of the threaded end of the and whack at with a big hammer . This can swell the bolt end so don't be stupid ,think your way through it as to NOT damage the bolt or nut.They can be very difficult to remove Good luck .