I have an 05 f250 4x4 with the 6.0 and when ever I accelerate hard from a stop it makes this bad grinding noise you can also feel it. Seems like it is coming from the front axle. It only does it from a stop or a very low speed ( less then 5mph) at 40 you can punch it and it doesn't do this. Hopefully someone can help me out here! Thanks in advance!

 

It sounds like something is rubbing like the driveshaft or the fan, etc. It won't do it at higher speeds because the enertia is largely overcome at that point.

 

It'll stop the grinding feeling and noise if I just slightly let up on the throttle. I did crawl under the truck again and one of the u-joints in the front driveshaft was slightly wore. I don't know if that would cause it or not but I wouldn't think so since I am in 2wd