I've never heard of anyone breaking one and there are loads of Hiluxs running turboed 3RZs, 1 & 2JZs and every kind of holden motor. I'm sure they have a limit but not one I've heard. Being the same diff housing as the 4WDs it means that there is a lot of different locker and LSD centers available, just talk to a 4WD shop about whats available. As for the clutch setup, its simply clutch, shim, clutch, shim using metal clutches. I don't really know any more than that about its setup. The rotary boys get them tightened with more shims. That and the interchangeable gears are the only mods I know for them.