So I finally bought a rear locker for my 4runner. I got the Aussie Locker (model XD-24930) from http://www.aussielocker.com. I also bought a front locker, but haven't gotten around to installing it yet.
I did a fair bit of research before making the purchase. The three main options for differential locking seemed to be: welded (spool), lunchbox lockers (ie. aussie, lockright, etc), and manually activated lockers (ie. ARB air locker, e-locker).
Welded, or spooled differentials essentially tie both axles together full-time. Neither wheel can spin faster than the other and for this reason going around corners on hard surfaces can suck (and eat tires). Since my 4runner is mostly just a weekend/bush/camper I did consider this route for a time. Welding is free, and a real spool can be picked up for under $100 if desired.
Manually activated lockers such as the ARB or e-locker from newer model 4runners are probably the most usable option. That said, they come with a cost. To buy front and rear ARB lockers plus all necessary hardware, you're looking at ~$3k (that's more than I paid for my truck)! Manually activated lockers allow the driver to select between open differential action, and fully locked or spooled. At the press of a button the the two axles are locked together, giving maximum traction. As nice as that would be, I pretty much immediately ruled out this option as I simply can't justify the cost. I have every intention of driving this truck into an early grave and don't plan on doing much pavement driving.
This all lead me to the lunchbox style locker. I read up on a number of different brands but eventually settled on the Aussie. All of the reviews I read online pointed to this as being my best option. The aussie works by engaging only when under load. This allows it to free-wheel around corners, but give full positive traction when needed.
Installation was fairly straight forward. I had never done any differential related work before, but everything went according to plan. Basically you just pop off the wheels, pull the hubs and axles, unbolt and drop the third member, and you're looking at the spider gears. The aussie unit goes in place of the stock gears and you end up throwing a lot of it away. I was surprised at how simple of a unit the Aussie is, it really only has two main main parts to it. I may write a bigger thread with details on the full installation at some point, but for now just know that it can easily be done in an afternoon by a couple of guys who don't really know what they're doing ;)
First impressions after the install are - wow. I can't believe I didn't do this sooner! Trails that used to give me a hard time are now a breeze. I'm having trouble finding an incline that will stop me! The bang for buck with this thing is unbelievable, I wouldn't have believed how much of a difference a locker could make before I tried one for myself. Being relatively new to the off-roading scene I did the basics like bigger tires, lift, and bush bars first. Had I known what a difference this Aussie would make though, it would have been my first purchase! Total cost was only a few hundred dollars, which includes shipping, diff oil and all.
Some pics from the install:
More pics.. I actually think the hardest part of this whole job was removing the brake drums. Those little bastards were so grooved it took a lot of prying!
The only downside of the locker that I've found so far is that it's made me over-confident :) I broke a brand new front axle on my first trip out, it was literally 3 days old! A solid axle swap is moving higher on my priority list every day. I'm almost considering not even installing the front locker and just waiting till I'm SAS'd.
Great post on the different options. You don't mention the working principle of the one you picked though. Is that a full-time limited slip differential, or can you lock/unlock it?
I have a bit of metal in my diff fluid when it gets changed, especially in the front... might be I have to do some diff work anyway in the near future.
The working principle took me forever to figure out. I sat there staring at the thing forever before I put it in, trying to figure out just how it works. Basically whenever force is applied to the axle, it pushes the locker apart from the inside out. That force locks the outer 'gears' or whatever you want to call them to the inner gears, and essentially binds both sides together. It isn't 'limited slip', because when you're on the throttle it doesn't ever slip, at all. It's just locked when you need it, and open when you don't.
I attached a picture I found of the same unit to give you some reference.
based on that picture, the axle gears and cam gears are the parts that click together and actually lock it. The axle gears are attached permanently to your axles, and the cam gears spin with the pin (not the little pins pictured, but the bigger one in the middle).
I have one of these as well and so far it has worked great.
Now I have to get one of these for my 3rd gen. I've got the factory elocker but it's broken (and all the wires have been cut for some reason by the previous owner). The cost of putting a new elocker in would be quite high, so I'll have to see if an aussie will fit in the stock elocker third - anyone know if it will?