4 wheel drive

If you were able to get it to go that fast in low, WOW! The worst thing that should have happened was a blown engine. It should have been reving into the redline area on the tach. As far as the transfer case, nothing should have happened there. Your problem sounds like it is actuator related. Have you checked to see if there is power to the actuator on the transfer case when you shift?

NOTE: If the engine is still running good, relax and we'll figure out the other issue. In the future, 4wd low range is designed for very slow speeds (about 25 max) when a lot of power is needed but not speed. Leave it in 4wd high if roads are bad and you must travel at higher speeds).