Driveshaft noise?

[Matt Suffern]

Hi all. I'm getting an intermittent scraping noise coming from the region just under the shifter area underneath the car. 

It seems to be louder at very low speeds, but this could just be because the normal wind and drivetrain noises haven't 
drowned it out yet. For instance, I can't hear it above, say, 20 mph, though it might still be there but I can't tell it apart from 
normal driving noises. 

It sounds for all the world like a heat shield is bent and rubbing on the driveshaft, but only every once in a while. There's 
no discernable pattern as far as when it occurs relative to when the car's cold or hot. It *does* seem to occur more 
frequently when I've just started the car and am driving off, though it also happens after I've been driving for a while, and, 
say, pull up slowly to a stoplight. 

I went out earlier today and felt around the exhaust and driveshaft in the vicinity of the noise under the car, but I couldn't 
find any interference, or even any tight clearances. 

Any ideas? Do I have a bearing/u-joint going bad?

Thanks and Merry Christmas,

Matt
'86 4kq
Chapel Hill, NC