I'm proposing doing this sort of procedure to a MITSU rear axle, not a Toyota...and it's no more work than a lot of the Yeepers go to for their axles, really. So many of them build the damn things from scratch...literally! It's bizarre that Jeeps have SUCH an aftermarket that you can build a brand-new Jeep from scratch, without a single part of it that ever saw the inside of a Willys, AMC, or Chrysler plant.
But yes, it'd be a lot of work, but certainly feasible, given what else is done on a regular basis.
...and yes, a Wagoneer D44 would work, but it's not a MITSU axle...maybe I'm just being stupid, but I think it's important to maintain as much Mitsu in our Monteros as we can. Yeah, we can drop a GM 4.3 with a GM auto, dual Atlas transfer cases, and D44 axles in...other 4WD vehicle owners do it all the time. But once you've done THAT, what do you have left that's still Mitsu? How can we say that the Montero/Pajero/Raider is a superior offroad vehicle, when all you have left of it is the frame and sheet metal? It's one thing to IMPROVE on the existing mechanicals or to replace stuff with other Mitsu parts (for example, Starquest turbo engines in the older Monteros are a GREAT solution), but to just REPLACE major assemblies, ESPECIALLY with American parts...well, it bothers me. It's UNSEEMLY, AND I think we can do better.
Besides, I'd think you'd have MUCH less windup if both differentials were absolutely identical, not just with *similar* ratios.
Toyota made 2WD one-ton pickups...not sure of the range of years. One of the engineers at the BoR here has one...looks like a normal Toyota from the outside, but has a "1 Ton" decal on the bed and tailgate. If I remember correctly, the axle shaft itself doesn't bear much of the weight...all it has to do is drive the wheel. There's a special name for this sort of axle, but I don't remember what it is...and something about this sort of axle makes it very well-suited to a front SAS conversion.