Detroit Locker (DET)
Probably the most durable design available, these are the king of traction differentials. Usually causes banging and clunking, but gives 100% lock-up whenever traction is needed. Unlocks when negotiating a turn so that the outer wheel can turn faster than the ring gear and the inside wheel, with no needed interaction from the driver. New Sof-Locker design has damping device to reduce banging and clunking, and includes a carrier case that is stronger than stock except in 2 applications, where the original factory carrier case is used. Only the 10.5" 14 bolt truck and the Nissan V6 designs use the factory carrier case and these cases are both very strong. (aftermarket) 1-year warranty

Eaton (EAT)
Clutch type, similar to Trac-Lok in design, yet far stronger and more aggressive. These units came as an original equipment option in 65-72 12T (12 bolt GM truck), 12P (12 bolt GM passenger), 8.2" GM pass, 63-79 Cast Iron Corvettes. The original OEM 12T case was very weak, but the new design replacement from Eaton is very strong. Four preload springs and two steel preload spring plates. Latest design uses HD nodular iron case, forged side and pinion gears, no-chatter, race-bred, carbon fiber clutches for extreme strength and longevity.

Old design, all steel clutches which are still available in 18 or 22 clutch designs for those who need more lock-up and are not bothered by clutch chatter. For even more lockup customization, there are also four levels of spring pressure available (3 from Eaton and a fourth from GM) that can be used to vary the clutch preload from 200 lbs. to 800 lbs. Originally used in mid-sixties GM muscle cars and trucks. This unit is now available for Ford applications and soon will be available for Dana Spicer, AMC, and Chrysler applications. They have a high tolerance for abuse in high horsepower vehicles. Recommended for everyday driving and severe off-road use (factory GM )

Equal-Lock
This was the first design limited slip used by Ford in both the 8" and 9" rearends. Except for new clutches, there are only used parts available now. This design is not aggressive and does not lock-up harder when more power is applied as most every other limited slip design does. Ford built two different Equal-lock designs. One uses four plain steel plates, three fiber lined plates, and one Belleville spring for preload. The other uses only three plain steel plates, two fiber-lined plates, and two Belleville spring plates. The design that uses two spring plates can only be converted to the single spring design with more clutches if the appropriate clutch hub is used to accommodate the higher number of clutch plates. Can be identified by five tab clutches (Ford Traction-Lock for the 8" and 9" use four tab clutches). (factory)

Traction-Lock (T/L)
(Also referred to as a Track-Lock, not to be mistaken with the Dana Spicer Trac-Lok) This is the second design limited slip that Ford used in both the 8-" and 9" rearend designs. It is a fairly good design for moderate horsepower applications. This is a clutch type design that uses four plain steel clutches, four fiber lined clutches, and one plate that is steel on one side and has fiber lining on the other side. It uses a two-piece case that looks very similar to the standard open carriers, except the parting line between the two case halves is covered by the left half that "wraps around" the right half. The parting line between the two halves on a standard case is easy to see and is not covered. Traction-Locks are not very aggressive and tend to wear out fairly quickly if used heavily.

Newer design Ford rearends such as the 7.5", 8.8", 9.75", 10.25", and 10.5" also can be ordered with Traction-Locks. These differentials use a one-piece case with two spider pinion gears, except for the heavy-duty 10.5" rearend, which uses three spider pinion gears. The 7.5" and 8.8" designs have soft clutches that tend to wear-out quickly and are not aggressive even when new. The 10.25" unit uses composite clutches that holdup fairly well, but it is not aggressive and tends to slip too much when needed off-road. Trac-Lok is a medium-duty limited slip and will hold up without breaking, but will wear out the clutches quickly under heavy-duty use. If the unit wears out it usually can be rebuilt. (factory)

Trac-Lok (T/L)
Built by Dana Spicer for use in Spicer rearends, AMC rearends, and 1998 & older 10.25" Ford rearends. The old design built up until about 1989 was weak. The 1990 and newer design is fairly strong and even rivals the Powr-Lok for impact durability, but the clutches do not provide as much lock-up force and tend to wear out in about 50,000 miles if used in the rear. Works better in the front of vehicles because it's not aggressive. The main selling points for this design are the fact that clutch chatter is almost non-existent, and it is very inexpensive. These two points make it a great unit for many applications and a very good value for the money. This unit makes a great front limited slip and works well for those who need a little extra traction but cannot tolerate clutch chatter. The Trac-Lok came factory installed in many models such as D28, D44, D60, AMC 20, AMC35, 10.25" Ford. The problem with this unit is that it is not very aggressive and power transfer is minimal. Also, 1988 and earlier units tend to break fairly easily. (1piece case, 2 pinion gears, and 2 tab clutches). (factory)

Powr-Lok (P/L)
This clutch type limited slip is the strongest and most aggressive limited slip differential available from Dana Spicer. It is a clutch type unit using floating cross shafts that ride up on ramps in the case. When power is applied, the shafts ride up the ramps and load the clutches for a positive engagement. A Powr-Lok will not lock up 100%, but it is a very durable unit that will hold up fairly well with tall tires. It can be rebuilt, and can be set up smooth or aggressive by changing the clutch design or stacking configuration. Powr-Loks are easily identified by their 2-piece case. They are a very strong unit due to the 4 spider gear design that provides twice as many teeth to carry the load as a 2 spider gear unit does. However, the case bolts can stretch or loosen after severe use over time. (4 pin, 4 tab clutches) (factory)

Toyota Race Development (TRD)
This is a really good Toyota differential. They operate on the same principal as the Powr-Lok. The clutches virtually never wear out. Sometimes this unit chatters depending on the specifications requested by the importer. They are sometimes imported in small quantities by various sources and are now distributed by Auburn Gear. (aftermarket) 1-year warranty

Detroit Truetrac (TT)
Based on the worm gear principal and works like clutch type positraction. Does not wear out, not recommended for tall tires over 33".

Detroit Truetracs are similar in design to the Gleason Torsen®, only the Truetracs hold up well with reasonably tall tires. They use worm wheel gears that work on the same principle as a worm gear. When the unit is loaded, the worm wheels are forced away from each other and against the case. They develop locking torque by the light friction between the worm wheels and the case. This light friction is multiplied by the ratio of the worm wheel which depends on the size of the worm wheel relative to the size of the side gear. The manufacturer can change the amount of torque biasing or lockup by simply changing the diameter of the gears, or the pitch and spiral of the teeth. A larger difference in the size for the worm wheels and side gears (smaller worm wheels and larger side gears) will increase the lockup force. Increasing the pitch and spiral of the teeth will also increase the lockup forces. Like everything, there is a limit as to how much lockup force is reasonable. Making the unit too "aggressive" will cause tire scrub during everyday driving and will cause the unit to wear out too quickly. All of the feedback that I have received from customers indicates that the unit works very well for mud and snow, while going unnoticed during every day driving. When used in situations like rocky trails where one wheel gets off the ground, the unit will not lock up 100%. Light application of the brakes will help the differential engage more transferring power to the tire that is still on the ground. For extreme situations where the vehicle will have one wheel in the air often a locking differential provides better power transfer to the wheel on the ground.

Detroit Truetracs are designed for medium duty 2WD and 4WD applications. They work well in the front and rear, and are so smooth that there is little or no hint of resistance in the steering wheel when used in front drive steering axles. Like the Gleason Torsen®, the Detroit Truetrac does not bang or clunk, has no clutch chatter, does not wear out like clutch type positractions, does not need limited slip additive, and needs no preload or clearance adjustments.

Almost sounds too good to be true doesn't it? The only drawbacks to the Truetracs are their inability to provide lockup 100% like a locking differential can. Although Gleason no longer makes the Torsen® differential, the Detroit Truetrac is a proven design that is available for many popular applications. (aftermarket) 1 yr warranty

Gleason Torsen
Worm gear type no longer made by Gleason, but a few models are build by Zexel Torsen. They are very similar to the Truetrac. (aftermarket)