MAJOR driveline noise, no fwd or reverse - WTF?

[RUSHNBOBO]

Originally Posted by cdig

I just picked up a 2004 GMC 2500HD, 6.0L AT. Bought it at auction for cheap (it was a theft recovery), figured i'd take a chance on it. Engine runs good, but when i put it in reverse or any drive gear, in 4wd or 2wd it doesn't even try to move, just get a very loud banging/crunching/grinding/gear stripping kind of noise...

Thanks for any insight!

Will the truck roll or move at all with transmission in neutral and transfer case engaged ? if so what do you hear ?