LSD's fall into two basic categories. Spin resistant & positive locking.

The Detroit Locker is the best known of the positive lockers & they work exceptionally well, but unless you have a 4wd or a drag car, then don't touch one with a barge pole. I fitted one to a Falcon /Warner rear axle assembly & tested it for some months as an official Telecom trial. In the hands of a skilled driver, they can be really good. In the hands of an average Joe, they can easily become the source of grief in the blink of an eye.

The spin resistant type is the most widely known & used. They use either spring loaded washer packs, or flat clutch disc setups. Basicly they use friction to give a partially locked diff.
I say partially as the spring pressure on the friction devices is supposed to be low enough to allow normal diff action when cornering, however, if one wheel slips, as in, when one wheel is on the sealed road, & one is in the mud, the friction to the axle on the road is enough to provide positive drive & allow you to reive on.
They effectively delay the point where one wheel breaks loose. You will need to abuse it pretty bad to loosen it up in a couple of months.

Ask 1200rallycar how long his axle lasted in his welded diff, & ask him to repeat his glowing recomendation for welded difs.