slight grinding on rear axle?

[Hoon Kim <hoon@pixar.com>]

So I've been hearing a little metallic grinding on my rear axle while  
in neutral that goes in and out randomly. I put the car on jack  
stands and when I turn the right rear wheel only, there is some  
resistance and it always turns the drive shaft. When I turn the left  
wheel there is random resistance and the drive shaft turns very very  
slightly. Anyone have any clue what it is and what to do to fix it?

The car runs fine however.

Any help could be greatly appreciated.

Hoon
'67 1600