problems with 94 Expl 4 wheel drive

Not a mechanic here, but am wondering how the 4-wheel drive works in a 94. I have the automatic system and it feels like the front grabs on the snow, however, I got it stuck once and the front wheels don't even spin. Is the 94 system a 40x60 percentage unit? If so, I'd think that the front would still engage and spin when stuck. Someone mentioned that the automatic hubs could be blown, but it feels like it grabs in the snow, could this be just the axle engaging, although the wheels aren't? Thanks for any and all help with this. I do appreciate it.

he first time I took mine out the front wheels dropped into a muddy rut and would not move. The hubs were shot. Replaced them with manual hubs instead of automatics because of the cost. You can get this done a a 4x4 shop, not the dealer.