Hello I own a 2006 ford ranger fx4 4.0L and I have noticed that when I let off the gas and just let it coast there is a noise in the front end that isn't really a grinding sound, but like a low growl. We have checked the axel bearings and they are find. My control arms/suspension is brand new. Any thoughts?

 

It only does it in 4x4, correct?

If so, that should be normal. Before I got my exhaust I heard the same thing. Its just the added resistance from power being transferred to the front axles.