Try google search engine. With the rebuild master kit, fluid, etc, add some more money. Also, try to add some more money, PERIOD. The better units are more like $400, not 300. Eaton, and Auburn both have a solid reputation. The eaton is higly recommended by the guys who put in some extra power, like superchargers and chips.
They all eventually need service, they all wear out some day. My eaton is still good, it gives about 100% / 60% full time, and swaps over less harsh than some cone types. Perfect??? Who knows. Better than an open diff?? Oh hell yeah. Be SURE to use the right diff fluid when you do this, or you will booger things up, and get all kinds of slip you wouldn't ant to deal with. A lot of shops make this mistake, and the guys feel their units aren't working properly.