"change but seems to spin on slightest snow cover", not sure what your trying to say.
to confirm if it has limited slip, block the front tires, jack up the near axle so both wheels are off the ground, take e-brake off, put transfercase in neutral, and turn the driveshaft. if the wheel turn in the same directions, then LS. if they spin in opposite directions, then no LS. you could also spin one of the tires and look for the same thing. sometimes if the LS is worn out, the wheels will spin the opposite directions and look as if you dont have limited slip.
or just change the fluid and look for LS, then add the friction modifier when if you need it.
as for fluid, i would just research and make your own choice. it seems everyone has there own opinion on whats best and its more of a personal choice. the correct weight should be in your owners manual and it also depends on whether you tow alot and what temperature the weather is in your area.
