There are plenty of people on here with welders, and i bet some even own nissans. I doubt though a toyota owner would weld it and even if they did they would probably use plastic rods or something similar
Which diff is it? if its the front, then drain the oil, make sure your hubs are out and a nissan owner should volunteer, if not pop along to a 4wd place like 4wd accessories or summit4wd and I imagine it wouldnt take long to zap it.
Mike