I have a 2005 fx4 crew cab and it is making a loud roaring noise. I cant really tell if it is coming from the front or back. It makes the noise as soon as i take off and gets louder with speed and keeps making the noise when you let off of the gas. It also makes the noise when the transmission sounds like it is down shifting. Any help at all would be really appreciated.Thanks Nick

 

it sounds like it could be coming from either the transmission or the rearend

 

Take a real good look at your u-joints and check that the yoke at the rear diff isn't loose. That's where I would start.

 

Everything in the u joints seem to be fine! On my way home this morning I was listening to see what it did and it makes the roaring noise (almost like loud road noise) coming from underneath! It did it when I mash the gas but when I let off it quit until it sounded like the trans was down shifting!

 

Internet diagnosis is difficult - why don't you take it to a shop and get their opinion?

 

pinion bearing, wheel bearing?