We find this question coming up a lot, so here is what we have learned from our own experience and what customers have told us. Remember you get what you pay for and each locker has its own advantages and disadvantages we will try to list all the advantages and disadvantages of each. Also this should be stated: before getting into locker choices if you daily drive your truck any locker that is not select-able will diminish on road driving characteristics. If you have a newer vehicle that you drive every day and expect to use your 4 wheel drive in the snow and ice on the road, consider a select-able locker as the only way to go. Full non select-able lockers can be dangerous in the snow and ice. Both tires turn at the same speed which results in the vehicle wanting to go straight even when you have the wheels turned. Also in a icy conditions with both wheels spinning at the same rate it causes the vehicle to slide and spin that much faster. For snow and ice using a limited slip or select-able locker is a much better option. So onto the advantages and disadvantages.
Lockright, Spartan, Aussie Lockers (AKA Lunchbox Lockers):
Advantages: Cheap, easy to install for backyard mechanic (in theory we will get into this in detail in the disadvantages) gives full traction when you need it, yet still allows you the ability to turn on the trail as it will unlock when you need it. We really think this is a good option in a front 60 for trail use. The Dana 60 carriers are very strong and can handle the load of hardcore use. Lockrights come with a 2 year warranty and Richmond is good about getting these warrantied. Spartan Lockers come with a 1 year warranty and are very good at being warrantied. Aussie Lockers carry a 2 year warranty and as of yet we have not warrantied one. Pins can break and the springs do wear out but they are easily replaceable and cheap to do so. For the price lunchbox lockers are are a great product they offer full cheap traction but will also unlock to aid in steering.
Disadvantages: The lunchbox locker relies on the strength of the carrier a weak carrier will literally rip in half. If your already overloading your current set-up with big tires and high horsepower, the carriers can fail. Ford 8.8 carriers and ten bolt carriers are good examples where we have seen this happen. Lunchbox lockers have poor street manners; not terrible, and each person has there own limits of acceptability, but we are building trucks to do awesome things offroad so sacrificing ride quality on the road is a fact of life. We do not recommend lunchbox lockers in any trucks that are used for towing. Reason being, a lunchbox locker unloads when off the gas and then relocks when you get back on the gas. This transfer translates to a slight to heavy pull to one side. The magnitude of this pull is really determined by suspension and wheel base. With a very loose suspension and short wheelbase this pull is very noticeable. And frankly sometimes dangerous if one is not accustomed to driving with one. With a tight suspension and long wheelbase it may be unnoticeable. As far as installation goes, some vehicles require the ring gear to be removed from the carrier in order to drop the crosshaft out. On vehicles with side adjusters such as 14 bolts, Chrysler rearends, and Toyota 3rds; the backlash will need to be reset to the factory specifications. In order to do so a dial indicator is required. For Toyota's, the ring gear needs to be removed to install the lunchbox locker and the backlash will need to be reset. In this case it is truly easier to put a full carrier locker in it.
Detroit lockers are tried and true, and they are extremely strong. They offer you full traction and come with a 1 year manufacturer warranty. They also unlock when turning allowing you turning ability on road and offroad. These lockers have built a great reputation because they are so tough. This is a true upgrade for a weak case. If your carrier is the weak link in your axle, after adding a Detroit it won't be.
Disadvantages: Much like a Lockright, Detroit have the same poor street manners, depending on application they can be very noisy when they unload, usually in a parking lot or when doing tight turning maneuvers. They will load and unload on the street, when you are on and off the gas. They are however usually less noticeable then Lockright's and suspension and wheel base play a large roll in the severity of the effect. The biggest downsize to the Detroit is if you break a shaft 90% of the time the clutch plate on the side of the broken shaft usually breaks from the recoil. This leaves you with a broken shaft and a broken locker. The locker can be repaired but these pieces are very expensive in relation to the cost of the locker, they are not proportional. A clutch plate usually is in the $160-$200 range. Another note is Detroit's customer service is sub par. Their warranties are usually very slow and parts can be very hard to come by, if you need a part you will need a very motivated vendor to get it for you. If you break a case on a Detroit, not real likely, but possible, just the case portion will cost you close to what a new locker will cost. Again Detroit's have a great reputation for being strong b/c they are but if your treading on weak axle shafts think about upgrading your shafts with the locker or you might be in very bad position ( broken locker+ broken shaft). These lockers are not highly recommended for tow rigs or vehicles driving in snow/ice road conditions.
Auburn: Just a blurb here since we do not have a whole lot of experience with these. Here is what we know: They are a great idea, and when I say great I mean great. Having a full time limited slip that transforms to full locker with a flick of a switch is an awesome idea. Auburn makes a great limited slip and makes some fantastic products. Their warranty programs are top notch and they typically have great customer service. The problems we have heard is when the locker portion of the differential is engaged it slides the side gear over towards center this takes away form the spline engagement of the axle shaft to side gear and stripped shafts is the result (This may be hearsay). They are priced right but their true worthiness is still in question with us. Don't count auburn out though, we think they will correct this problem and manufacture a better differential. They are again a great company that manufacturers awesome products right here in the USA.
Advantages: They are one of the toughest lockers ever built and are a 100% forged differential. The mechanical linkage with the cable is simple and effective. You can engage and disengage when you need to, making them useful on road and offroad. Go to the track or offroad, pull cable for full traction. Drive home push it in for an open diff. A properly routed cable that is maintained(oiled much like a motorcycle throttle cable) can give you many years or quality service.
The cable can be problematic and they do require maintenance and or replacement. A properly routed cable is essential. It needs a fairly straight shot, and can absolutely not be routed near any heat source. The cable sheath will act like heat shrink if routed to close to the exhaust and the cable will seize in the sheath. Their expense is a disadvantage but this comes from it being a very well built differential.
Advantages: We are not going to hide the fact that we think this is the best locker on the market. Of course it is also one of the most expensive. It is the fastest locking and unlocking differential on the market. If you are offroad and need to make a tight turn flick it off make your turn and flick it back on. They are extremely strong; as strong as any differential on the market if not the strongest. We have never seen one break. If your case is the weak link in your axle, with an ARB lock that will no longer be the case. If you have a newer vehicle that you drive everyday, installing the ARB will not impair its road qualities at all, just leave it off. In snow/ice conditions on the road an open diff is the safest way to travel, the ARB allows you to have that open diff. If you need to pull someone out of the ditch lock it in. If anything does go wrong with your locker or the accessories, replacement parts are easy to get and relatively cheap. ARB's customer service and warranty programs are awesome (2 year warranty). If you buy an ARB compressor with the locker, between the two purchases you have everything you need to actuate the locker. The compressor is very easy to install. Simply mount the compressor in the desired location and wire it with the provided harness. The electrical harness is pre-built for you to run the compressor switch and two locker switches, so you can easily add another locker later if you so choose. ARB's come with vehicle specific instructions that are easy to read and very explicit. If money is not a factor ARB is the only option for strength, reliability and safety. There is no downside to an ARB locker if installed properly.
Disadvantages: The ARB needs to be installed by a quality professional with experience installing diffs, a do it yourself-er can install and we will answer tech questions, but realize this is not a slap it in and go locker. If an ARB is installed properly it will outlast your truck problem free. The airlines need to be routed as to not get caught by rocks, suspension travel, ect. The air lines also need to be protected from chafing and direct heat sources. Their expense is also a downside, we know about budgets, but usually doing it right the first time saves money in the long run.