Anyone ever had a similar problem? I will be drivejng the truck down the road and suddenly you will loose drivetrain power and a loud grinding noise will appear and will continue until you slow down and put in park the 4x4 shifter is also shaking when this happens and it sounds awful the grinding noise also seems to get louder and faster as you slow down. 84 f-150 302 4x4 c-6 new process 208 t-case

 

Could be a tail shaft bearing gone out. Or the input on the t-case