Think he's on about a 1.5way or 2way LSD, Personally i'd recomend 1.5way one, but it depends on what you'll be using the car for mainly, drag, track or street driving
a 1.5 way lsd will lock the wheels under power, a 2 way lsd will lock them on power and on slowing down, a 2way is more for a track car, its quite harsh for road use, but mine came with it in, so i deal with it lol