Go for the swap man. Buy the diff for $100, and then you have all the time in the world to hunt down an LSD, without rushing and overpaying. Then swap it in and sell the original diff you bought.
LSD is awesome for winter. I don't think I would have gotten through this winter without it. I do a lot of snowboarding, so lots of snow to drive through. Sure the LSD throws the tail a bit, but once you get used to it (and practice in parking lots) it becomes second nature. I can basically slide for 10-20m without flinching and remaining in full control while my buddy is shitting his pants. Of course it helps if you drive slow
. But I haven't gotten stuck in deep snow or anything, because double the traction is a good thing.