About to build my diff- What limited slip?

Like the title says- the 6 gear Tru-Trac looks nice but does it work well and for how long? What do you recommend that's actually available? Oh and this is for a more road course- spirited driving application- not slicks and dragstrip stuff. More like real street use but don't want clicking/whining/chattering or axle breakers. Real world advice would be fantastic. Cheers, J.Rob