Open diff or limited slip

Make sure you know the difference between an open diff, a limited slip, and a locker. Open diff = one wheel slips, all the power goes to it and the vehicle won't move. Limited slip = one wheel slips, power goes to the non-slipping wheel and you get moving again. Locker = both wheels are virtually locked together. Lockers are almost never used on the street, regardless of the conditions. They're common on off-road vehicles where you want to keep moving in very rough terrain or even if one or more wheels are off the ground. On ice or very slippery conditions, lockers are often a more squirrely if the road slopes to the side since both wheels are turning at the same speed. A LSD is better in these conditions as the one wheel that isn't driving tends to hold the vehicle a bit better. I'd definitely go with a LSD, not open and not locked unless you're really into off-roading in severe terrain.