Okay, so I just remembered this one thing. Tell me if it at all sounds relevant. When I bought the truck the guy said he had a new U-Joint for it but hadn't installed it yet. He gave me the U-Joint and I still haven't installed it yet. Is it possible that the U-Joint that is on the truck is going bad and could it make the kind of grinding sound I have been describing?? Thanks guys.

 

maybe. you should put it up in jack stands with helper/driver and let the drive train turn while you look and listen. inspect u-joint with truck off, in neutral, wiggle u-joint. should be no movement and seals intact. any loosness is bad. u-joints usually squeak, not grind.

 

Torque Converter gets my vote too. U joints will shake the crud out of you if as bad as you say. But, check them anyway like dhvaughan says.