For the US, the 01-03 were basically mechanically the same for the XL7. The mechanicals didn't quite change until 04. For the world, the 3rd generation (Vitara) has many different underpinnings. There has been shown even a rear D44 axle setup stock on a GV in Taiwan.
I do believe that if the external housing is different, that the inner parts will probably will be too, at some extent. Figuring the cv shafts are the same to keep assembly and part costs minimal. Same for the pinion yoke. But figure, if the external is dramatically different, then how does it bolt into the later year frame? I don't know.
My US model front axle housing both aluminum and the cast steel, look exactly the same. I'll shoot some pics of the swap next week Friday.