So I have a couple of questions, I have a 2003 F-250 7.3L that has a 4 inch lift with 35's under it. The vibration im feeling is at 55mph the goes away at 65 the comes back around freeway speeds 75mph and also i can hear a humming noise around 40mph. I feel it both in the steering wheel as well as the rest of the truck. I have replaced and lowered about 1 inch (for the lift) the carryer bearing and just had my ball joints replaced. At 65mph i can feel (very faint) something that kind of feels like a bearing might be going out, kinda like this (grind...gone..grind..gone) but the it is pretty steady and quick. Any ideas what this could be?

Also under heavy exceleration i feel the truck shutter, and it is only maybe 1/4 as bad with the 4X4 kicked in (I know thats bad to do i was only doing it for test purposes). As i said i lowered the carryer bearing do you guys think i need to lower it more? Or would it be something else?