Unlike an open diff when it binds the spider gears will turn and release the bind. If you have a locker it will ratchet when it binds. A spool will scuff the tires to fix the bind. Now your tcase cannot release the bind that occurs from front to rear since both the front and rear turn at the same time. If you were to jack the front off the ground that would release the bind but since you have hub locks you can just turn them to the open position. Or you can just back up until the bind is reversed. Unlike AWD vehicles that have a slip feature intigrated into the tcase a Toyota tcase is a direct drive and there is no slip. Most importantly if you drive on dry pavement with it in 4wd anything and the hubs are locked you are asking for a failure.
Great answer thank u. Also when i am in 2wd at the begining of every gear exept 5th you can hear a clunk that comes from what i am suspecting the rear. Is this normal with the 85 pickups? i took the third out and took it down to the local shop and they said all was fine.
Also what can cause vibrations when i let off the gas in any gear. Like it vibrates enough to make your vision shake and than if i turn the sterring wheel to the point to wear i have resistance wile going down the road the steering wheel with shake.