Had alot of ice this morning and was driving about 50 mph in 4hi with OD off. Front end locked up sending me sliding all over the place. Managed to keep it on the road so no other damage but what happened? Shortly before this It made a slight grind/squeek but I figured it was just a little ice on the brakes. I don't know too much about transfer case's, hubs etc... so is this a locked up transfer case, hub or what? Put it in 2wd and it drives fane, try 4x4 again and it won't move. Any advice is appreciated

 

Lift and support front so wheels are off the ground. Disconnect the front drive shaft at the transfer case. Tranny in park engine running t-case in 2 Hi try turning the front drive shaft. If it turns the transfer case is binding in 4x4 if it doesn't the front axle is binding in 4x4.