Adding to the above posts, Torsen we have in our S are very reliable and low maintenance. They work when there is torque difference between the left and right rear...so they are better @ corner entry and mid corner and not as good at the exit. Torsen also have more friction than mechanical LSD. On the other hand, the Kaaz and Cusco are mechanical LSDs, which work very well and to specific applications like 1way, 1.5way and 2way depending what you are looking for...but they are noisy, needs lots of maintenance...not really ideal for street application. (try making a right hand turn at a stoplight slowly from dead stop...sounds like your rearend had fallen out...)

 

04 does have the same ratio i belive