I have a D44 from a '66 IH Travelall that has the same bolt pattern as XJ/MJ, but it has 2 piece shafts and is @5" wider.
Derr. Got sidetracked! (cross country flying can mess with the mind, especially if you get a sinus infection in the process!)
There is an axle tube brace available (goes over the pumpkin) and welding the tubes so they can't pull out of the pumpkin is mandatory, even on FSJs