i have a 1991 ford explorer 4x4 v-6. ever since about a month ago i notice a crunch when i turn my steering wheel back and forth in park. and when im driving down the road it sounds like i have a bad wheel bearing but i checked them and they were fine. when i reach speed at about 45 or up this loud vibrating noise can be felt/heard comming from the front end. im thinkin its bad ujoints because the tailshaft bearings move up and down side to side i dont think they're suppose to do this. or i might just need to get another front rearend. any suggestions?? the vibration gets louder when faster quieter when i slow down..