Have you put the car on a lift so that the right front wheel is hanging free and then try to move it to reproduce the sound? Violently moving the wheel up and down to simulate a bump may help you localize the noise. Also there is that plate that covers the steering rack and brake master cylinder. Is that bolted on tight?

You will have to remove the top nut ( in the trunk) and push the strut down. You might be able to just push it out of the mount and then raise the top shock cover to get at the gland nut without having to tilt the strut out of the wheel well.
My car had a thump when i bought it and tightening the gland nut fixed it.

Yes, car has been on the lift for the past year. Haven't tried too violently to shake it as I'm concerned about knocking it off the lift, but I did closely visually inspect everything in that area with nothing obvious revealing itself.

Yes, the bash-plate is bolted down securely. I removed/replaced it when I swapped out the tie-rods.

Well...that's the only thing I haven't inspected. Will give it a go and see what happens.

+1 on wheel bearings that someone mentioned near the top

If the car was rolled around without the transmission the wheel bearings will need to be replaced. Cost me roughly 300 bucks. Problem solved :)

Does it have Bilstein struts? IN addition to the top gland nut (my first thought) there is a strut tube locating bushing inside Bilstein struts that can wear out.

Rolling around a car without the trans will destroy the front wheel bearings? :confused:

Regardless, tranny hasn't been out of the car since it was new.

Umm...don't remember. I think they're green so that's makes them....Bilstein?

right, green=bilsteins.

In a different car, it made the same noise when the bushings in the strut top were wore out.

this happened to me on my '88, and thankfully it was the 2 nuts tightening the front belly pan were loose - after a bit of driving...i know it sounds too simple, but we cannot be above everything...worth a try, anyway...

Car has only been on the ground one week. Before putting the wheels on, I replaced the tie-rods and installed the Elephant Racing anti-bump stop "kit". Trust me, the belly pan is tightened to factory specs. "Ka-thunk" was there before all this work and remains the same.

Trying to get to the "gland nut" now...

Take the cat out of the dryer.

Have you checked for worn down or damaged strut spindle.

Fixed it! As some recommended here...check the simple things first. I couldn't lower the strut out of the top mount as my car is slammed. When I put the strut top nut back where it was, I noticed, compared to the driver's side, there was much less thread sticking out (1/2" vs. 3/4").

I cranked down on the nut until it matched the other side, then took it for a spin. No more "ka-thunk"! Nut was loose this entire time... http://fc01.deviantart.net/fs28/f/20...y_death_au.gif

Sweet, and congrats bro