Make sure that you remove the carter key & lock nut before you try to remove the big nut from the drive shaft,I don't know how much torque it takes to remove the nut, but i can tell you if you don't have a impact wrench to remove ,then get yourself a piece of pipe about three foot long ,put it over your rachet handle and pull down until it breaks a loose.Once it breaks a loose it will come offf easy.When your tighten it back up ,tighten it has much as you can with the rachet then put the pipe back on it and give it a big pull it that will be good enough.