I'm not sure why they didn't put it in the front other than to save money I just had it installed in mine it was $1500 installed for both front and rear this information is off of some of the papers the gave me.
Limited-slip diffs (also known generically as "posis" from the GM-trademarked Posi-Traction) offer the flexibility of allowing wheelspeed differentiation for cornering but "connect" the axle shafts when either side-to-side torque difference or wheelspeed exceeds a certain point. Most LSDs use friction between the differential case and side gears to connect the axles as opposed to lockers' meshing teeth. Generally, limited-slips are smoother and quieter on the pavement and inflict less tire wear than lockers because they transfer less torque per side. This is why some manufacturers recommend their LSDs for use in front axles.
In technical terms, limited-slips' design intent is to transfer more torque to the wheel with traction, a process called "torque biasing": the available ring-gear torque that a given differential can transfer to one wheel when the other one has reduced traction. Open diffs have 1:1 torque biasing; a traction diff with a 2:1 torque bias would transfer twice as much of the ring-gear torque to the wheel with traction as the one without.
Generally, limited-slips are one of four designs: clutch-type, cone-type, the hybrid limited-slip/locker Eaton Gov-Lok, and planetary-type. Clutch-type limited-slips are the most common and use spring-loaded clutch packs between the diff case and side gears to transfer some of the ring-gear torque to the tire with less traction. When traction loss is sensed, the diff's clutches transfer the power to the other side by driving that side's side gears. The spiders gears spread the side gears, which in turn exert force on the clutch plates. Increased load increases the pressure against the clutch plates, which transmits power to the wheel with traction.
Preload is provided by springs-the stiffer the spring/higher the load, the less wheelspeed differentiation the limited-slip allows, making it closer to the locker end of the traction-diff spectrum than the open-diff end. Clutch-type limited-slips typically require a friction additive to the diff oil for optimal operation. However, the clutches and friction area can wear down over time.
Cone-type limited-slips are manufactured by Auburn Gear. These units use "cones" that attach to the backside of the side gears that nest in machined surfaces in the diff case. Under load, the side gear wedges itself to the case. Because this design requires less force to lock the side gears to the diff case and there aren't any clutch plates to wear out, cone-type units typically enjoy long life.
Another limited-slip approach is Eaton's Automatic Locking Differential ("Gov-Lok"), which is a factory rearend option in many GM-built trucks. This diff uses "governors" to detect differences in axle-shaft speed, and its gears are activated by cam weights and friction discs when speeds differ by approximately 100 rpm, thus sending torque to the slower side. When "locked," the Eaton unit turns both end at the same rate, much like a locker. However, spring-loaded flyweights keep the units from locking at over 20 mph for safer cornering. Designed for stock applications, field reports say that the Gov-Lok can give up the ghost on trucks that have modified engines and oversized tires. The unit is also more costly than other limited-slips because of its complicated design and numerous internal parts.
Finally, the Detroit TrueTrac is a "compound planetary gear" unit that uses dynamic loading instead of clutches or cones to transmit torque to the unit's pinion gears. Because the TrueTrac has no springs/preload, light brake pressure can help transfer the torque.
Hope it helps
