Looked in the ASA and found that the entire axle housings have the same part number except between leaf and shock. The carrier is what's different. I also looked at my newer Montero and the air hookup is on the carrier housing. I'm going to assume it's the same way on the MS. I'm just hoping axle shafts will be compatible. I can't really find info on them besides just guessing at part numbers.

I took the entire axle from a 98 Montero Sport and put it in my 87 Raider. Bolted right in. Had to mess with the parking brake cables, crossing them and anchoring them with zip ties. Then had a shop put the rear u joint from the Sport it's huge comparatively. Disc brakes upgrade, and air locker. Why you'd bother putting an air locker on drum brake axle is beyond me.

I meant getting locking carrier from car-part.com shipped to save money over entire axle. I have non-locking MS axle housing with discs right next to me for cheap. For entire locking setups it's expensive plus lots to ship.

Picked up the 99 Montero Sport axle but the one with 4.6 and locking was gone. I have a 4.2 geared one. Going to order locking differential carrier from car-part.com and rig up some kind of fish pump or see if they have the compressor to engage the locker.

I'll keep this thread updated if possible.

As I work on and research this more I am only getting more confused here. Am I a pioneer in doing this or something? I can't get a straight answer anywhere.

In looking at mitsu part #s there are some sites that list the leaf spring axle as having only two types of axle shafts, with and without ABS. In the coil sprung axle it lists between locking and non-locking. Some sites list the leaf sprung axle axle shafts as both "with locking and without locking" and some just say "without locking" and have the same part numbers.

I have read on other posts where an axle shaft is a different length, but they were talking about coil sprung locking swaps.

Does anyone know for sure if I can swap in a MS locking carrier into this leaf sprung housing or is it something I just have to risk? It's going to be an expensive guess and I'd just like to know. I've searched and looked everywhere.

I've done a lot of reading on this so I can source parts for a disc axle swap on my Mighty Max. The good news is, most of this stuff looks to be interchangeable as long as you stay within the same axle size. 4 cyl 8", 3.0 V6 9" and 3.5 V6 9.5".

I bought an entire leaf sprung, 9.5" locking axle from a 99 Sport. The internal parts from that all interchange with the 3.5L, 9.5" coil sprung axles.

ASA shows the pre-2000 3.0 Sports were also available with locking diffs. They seem less common than the 3.5s, but they're out there.

The differential carrier and the actual locking diff are common to both the Sport, and the full size Montero. ASA shows the part numbers are the same for K96W / 3.0 Sport and V43W / 3.0 Montero. So you should be able to pick up a carrier assembly from either truck and be ok.

The axle shafts are specific to the locking diff and the Sport. They're different right to left when you have the locker. The part numbers don't interchange with the full size Montero. That doesn't necessarily mean they won't fit, but it looks like you'd be taking a shot in the dark here.

I've looked for 3.0, locking Sport axles. They're uncommon and expensive. The extra effort to get the 3.5 axle to fit was an easy trade off given that I can actually find those.

Thanks. I spent forever researching and calling the other day and my budget is slim so I went ahead and just got a proper geared open diff for cheap. Cheapest I found locking carrier was $250 + axle shafts and the places with the "locking" axle shafts didn't seem to know what they had. This is still a good project for what it gets you, I just have a third kid on the way and 4 cars. Working with the 3.5 9.5" axle like you did may be the way to go. More information on them.

Here are the part numbers for the axle shafts in 3.0 9" locking diffs.
mr377500
mr377501

It looks like the open/lsd axle shafts use MR377495 for both sides (if you have abs).