I know this will be of no help to you, but I found the source of a similar rattle in my 2.1 today. I was installing a cylinder in the block in the car when I spotted something odd-looking in the grille below the rear bumper--turned out to be a craftsman stubby screwdriver. It will have to sound better without that in there. 

Check for loose muffler mounts and lose sheet metal. 

Jim

On Oct 29, 2012, at 7:04 PM, Gene P <olgreywoof@GMAIL.COM> wrote:

> ... and you know how annoying and embarrassing that can be.
> 
> 87 2WD hardtop that has just had axles pulled, all 4 new CVs (GKN) and
> bearings greased.  There is a persistent but not constant rattle that
> sounds like it's rear and underneath.  It is not a rotation noise, but
> is set off by the slightest road bumps.  Running is smooth, no
> indication anything is wrong except the noise.  I've been underneath and
> in the engine compartment finding cables, brackets, anything that can
> move and make noise and tying things off.  And I just jacked it up again
> and turned and tugged wheels, all smooth and tight, no bearing play.  I
> have 190 miles around town now on the new CVs.
> 
> What else can I check?  And, should I quit thinking about the work
> that's just been done and be looking at suspension stuff?  How would I
> check bushings for noise?
> 
> Or should I just turn up the radio...