Yeah as long as the gearing is the same I think that would work. You have a v6 right? That makes things a bit easier because Montero's have the coil sprung rear instead of the old 4cyl leaf setup, you generaly have more options. Only some Montero Sports have the leaf setup.

I remember an old thread where someone was telling me you might have to drill the pinion flange on the axle to bolt up the driveshaft. I have no idea which flanges are different and when you have to do that, or if you can just mix and match parts from each driveshaft. I might know more next week when I have everything.