When I am driving down the road (could be 15 mph or 65 mph) I get a grinding noise out of my truck. Truck is a 2004 F-150 FX4. First time it happened I pulled over to check to make sure I wasn’t dragging anything and I wasn’t. I didnt think much of it bacuse it was dark and figured I ran over something. It didn’t happen again for another month or so and now it is happening on a weekly basis. Sometime’s it will happen for just a second and sometime it will not stop till I slow down to about 5 mph and then there is a grip thump noise. Also I can make the noise stop it stop by switching into 4×4. It never happens in 4×4 alone. I read about it and thought it was the switch for the transfer case so I took it in to have it worked on. The shop came back and said it was the transfer case motor and replaced that. I drove it the next day and it is still making the noise. Again this happens maybe once a week and I can never anticipate it happening. The transmission works great. I love this truck and besides this it is perfect for me.