I have a 2001 ram 1500 4X4 that is making a rumbling/growling noise in the front end. It is loudest at 60 km/h and can also be felt through the floor. When driving at 60 km/h the noise comes and goes if you turn the steering wheel back and forth. It sounds like either gear mesh noise or maybe a bad axle bearing. I have jacked up the front end and checked u-joints and axle bearings but couldn't find anything wrong. I have also replaced the front diff oil and checked the condition of the gears. The oil was clean and the gears looked OK. Has anybody else had this problem? Any help would be greatly appreciated.