580B Torque Tube gasket

I am new to the forum and have tried the search button but couldn't find the info I need. I have a 1973 580B that has a leak between the torque tube and the transmission. It leaks all the fluid out of the torque tube over night. I have the gasket but I am not sure the best way to install it. I have been told to take the backhoe off and split it that way but I have also been told not to over complicate it and just unbolt the torque tube from the tranny and slip the new gasket in. I also was told to cut the top of the gasket and slip it in. Any advice would be much appreciated. Thanks in advanced!