Is limited slip or a locker worth it for me?

[seattle gmc]

I have a 2wd Z71 07 silverado 1500HD classic. I will be moving back home to Idaho next month, and im a bit worried about driving my truck in the snow next winter. They had a lot more than average snow fall this last winter.

I was thinking that if i got a locker or limited slip set up, i might get some help in the traction department. I know nothing of rearends, so howhard would it be to add something like this to my truck? How much would something like this cost?

Im pretty sure my truck has an open diff with 373 gears. Im also planing on picking up aother set of rims and getting some studded tires. let me know what you guys think. I will try to attach a pic of my trucks spid.