'84 5kS goes ka-thunk

[Michael Spiers <mikes@specnet.com>]

Alright, the NET seems to be bored, judging by all the traffic on "I blew away
this & that in my Audi/BMW/Grumman Canoe" so I've got a techy question for
y'all to chew on.  Drivin' around the beat-up, 11 year old, 210,000 mile,
original engine/transmission/drivetrain-in-general 5kS this weekend (which,
incedentally, will take any of yer hopped-up Audi's, in reverse even), it seems
she's developed quite the obnoxious thunking sound at about 30 MPH.  Ann calls
it a "Warble."  The noise gains repetitions the faster ya go, but isn't really
noticeable 'till 30 or so.  The steering wheel does NOT shimmy, either when
accelerating, holding speed, or braking, no matter what rate you are doing any
of the above (damn thing tracks straighter than my TQ...)  The car itself does
not stutter or shudder when either accelerating, holding speed, or braking, no
matter what rate you are doing any of the above.  At speeds up 'till 90MPH the
car holds straight & chatter-free, and doesn't shake or anything, leaving me to
believe that the tires are balanced & the car is in decent alignment.  It's
been 50 - 75 degrees in Colorado recently (before this weekend anyhow,) and Ann
said the noise has been there for quite some time, so it's not snow/ice
somewhere it shouldn't be.  The noise is not dependant upon engine speed,
transmission gear, whether I'm accelerating or braking, turning left or right
or going straight.  I don't believe it to be wheel bearings, simply because
when the bearings went south on my TQ they made a significantly different noise
than the 5kS does (more of a whining than a thunking), and on my TQ they only
made noise turning a certain direction.  I don't believe it to be warped
rotors, because the noise does not change when braking hard, normal, or not at
all.  The noise is louder on the drivers side of the car, but sounds as if it's
coming from the centre of the vehicle, both on the drivers side & on the
passenger side.  If it had a driveshaft I'd blame it on that, but it doesn't.
 I don't believe it to be U-joints, outer or inner, because the noise does not
change if I floor it or if I'm doing 60 in third & let off the gas pedal.  Oh
yeah, it's a 5 speed.  Answers anyone?  Ideas even?  Many thanks!  (And, BTW,
just kidding about dusting every car on this list.  I don't think that car
could out accelerate me on my mountain bike...)  TIA for any clues!

-- 
-Mike
mikes@specnet.com
mks107@psuvm.psu.edu
87 5000CS TQ
84 5000S (2,000 miles away and a mile high)
90 80 (sibling's mode of transportation I get lynched into working on)