Delphic Reason
Is it used, refurbished?... If you don't mind me asking, how much did you get it for?... I am looking to buy the same thing for my S13 Coupe... I'm also wondering what the cost of instalation would run, roughly?... I'll probably end up swapping it out myself, but if the instalation isn't too crazy, I might save myself some trouble...
Installation of a differential pumpkin isn't hard, there are four bolts that link up to the driveshaft and six bolts on each output shaft area, then there are two more where the differential is held onto the chassis. If you are swapping the differential inside the pumpkin then there are two bolts on both sides that you will clearly see, make sure you knock out the output shafts with a hammer, pending on each pumpkin, you might have to hit harder to pull it out. after removing those and the four bolts, you can get the differential out of the pumpkin. Remove the ring gear that is attached by bolts and attach the ring gear onto the viscous differential, then reverse the process. If you open a pumpkin, DO NOT BREATHE! Gear oil is the worst smelling thing ever! Remeber to not use synthetic oils too.
But anyway...
Why go viscous? Viscous over time becomes an open differential when it heats up and the gear oil loses its thickness. Viscous requires the gear oil to be in motion in order to spin the other wheel. It is totally relying on fluid motion to spin both wheels at the same direction, also it will only do this when traction is lost. After a while it heats up and the fluid heats up as well, and anyone that has taken basic chemistry knows that when a thick fluid (80W 5) heats up it becomes thinner thus not be able to spin the viscous differential.
For me, I run a Tomei 2 way LSD. It's a mechanical clutch type of lsd that engages as soon as torque is put on it. It uses clutch plates to lock up to spin both wheels, thus no need to lose traction just to spin both tires, and there is no fluid heating problem. However, mechanical LSDs aren't cheap, ranging from 800-1400, however, they are the only way to go. If you want to learn off a vLSD first then move to a clutch type, you will change your driving style completely, thus buying that vLSD first is not a good investment. Save your money, and get a clutch type whether it be KaAz, Nismo, Tomei, Cusco, etc.