I am in need of help. I have 2007 5.7 SR5 4x4. When I shift into 4HI it grinds around the transfer case until the 4x4 engages. There are no flashing lights on the dash. It drives fine in 4HI. When I shift back to 2HI there is a droning/vibration sound at slower speeds that can be felt a little in the steering wheel and in the floor boards around me feet. This vibration comes and goes. It is currently not vibrating at all. It grinds every time I try to put it into 4 HI. It only grinds into 4HI while moving. When I actuate the 4x4 with the truck stopped, the 4x4 engages perfectly. Any suggestions?