command trac slop

got under my 98 4.0 4wd to check out the u joints, ive been having vibration above 40mph for a while. i put it in neutral w/ the p-brake on, and twisted both front and back drive shafts. im getting about 5-10 degrees of play in both axels, but the u joints dont seem to be the week point. i can hear slightly some movement in the t-case. Is this normal? i also have a slight whining that seems to come from the front of the car, it picks up w/ speed. whats the deal? thanks!