@SER_GTR: actually, youre explaining a Torque biasing diferential. an LSD is slightly different. it wont distribute the torque equally. what happens in a normal differential is, when one wheel has no grip, it will keep spinning while the other wheel wont move at all. e.g. put up one wheel on a jack, start the car and put it in gear. the wheel which is not touching the ground will start moving; but the car wont move. this is cuz of the diff. an LSD will give some power to the other wheel as well! in other words, the differential will have a limited amount of slip. NOT complete slip. this gives a car better control in turns cuz the inner wheel wont spin as much, thus robbing the outer wheel of torque. it also helps in launcing the car from a standstill, but a Torque biasing differential is better for launches.
thats what i think the difference is. comments are welcome.
MSD is indeed a brand name for ignition systems (and maybe other thingies too).