Grinding noise reminds you of driving with bad rotors and no breaks. The four wheel drive is trying to engage on it's own under various conditions.Towing,not towing, 5 mph,50mph. It happens intermittently so the dealership can't here it wont fix it. Ford is jerking me around about the repairs. So here I sit with 12,000 miles on a truck I bought in nov. of 2008 with hub problems. I am looking for people with similar problems to email me. They want me to drop it off at a dealer with no rental car and let them drive it for one mile or 100 miles until they hear the noise. Then they will schedule a ford engineer out to drive it and then try to come up with a fix. All at my lose of a truck. So if it takes more than a couple of days I must cancel my vacations because I use this truck to tow my 5th wheel all over Michigan.