Erm, I think we have a crossed wire here
I was talking about swapping the entire axle (tube, diff, pumpkin, swivels, hubs, brakes etc) not just the diff /3rd member as the yanks like to call it.
The LC80 axles are wider track, or at least when I looked closesly into it they were about 2" or so wider, of course I may be mistaken, it was ~18 months ago I looked into it
As for strength, the difference in shock loading a 35" wheel or shock loading a 29" wheel is massive, and this is where a lot of breakages occur, rather than application of torque whilst driving it.
*edit* LC80 axles are 63.5" wide, LR coil sprung variants are 58.5" wide, so that's 2.5" each side, meaning no need for silly offset wheels once fitted