Yesterday driving my 93 grand cherokee and 4 times at highway or near highway speeds (above 45mph) a very violent shudder. Started at different speeds. Can not tell if anything triggered it. Sometimes straight/bump/braking. Slowed down at around 25 mph, stops. Then I can accellerate and all is smooth again. Very random, but troubling. I think either a problem with transfer case or ABS.

Any thoughts on this one is appreciated. No lights come up during this shudder.