I'm looking for a diagnosis on this. I have a 98 F150 w/108K on it. The 4WD would not engage prior to two weeks ago. I could hear the transfer case engage but the wheels were free. I ordered the accuator for the front differential figuring that was the problem. That part is on backorder and I haven't gotten it yet. Two weeks ago I was rear-ended (minor damage). That must have jarred something loose because when I tried the 4WD it engaged fully. Now, it won't fully disengage. The wheels are now free (no bind when I turn), but the thruck starts to vibrate at 60mph and feels like it is in 4wd. What do you think? I should note that the accident damage has been fixed and it is not accident related that the vibration is there. It is defintely 4wd related. Also, the truck will now go into and out of 4wd as it should, except for something hanging up. Thanks.