I have a 94 p/u, 3.0, auto trans, no a.d.d., manual hubs. When trans oil is cold, 4wd works, as soon as it warms up, no 4wd, low or high range. Transfer case range selector works, just won't transfer power to front driveshaft. With all four wheels in air, oil cold, I can't hold front driveshaft stopped, as soon as oil warms, i can grab it with my hands and stop it from spinning. Any ideas?