scott05law

I have an 07 Tahoe 4x4 and when I hit 30 mph, a vibration starts and gets worse as I get faster. When I hit about 70 I hear a vibration noise and when I let off the gas, the sound and vibration goes away, but comes back as soon as I hit the gas pedal again. In 4x4 mode the vibration is barely there. I can only put the the truck in high 4x4 mode, but not low 4x4. The low 4x4 won't engage.