I own a 1998 Pontiac Bonneville SSE fully loaded, not supercharged. For the past several weeks I've noticed a clunking sound coming from the driver side, under floorboard. This now occurs during every stop and go, and every turn. I was told it was probably the rack part of my steering. I got a second opinion that it was my front struts. Having more than 150k miles, I replaced them. (I just replaced rear ones last year. One of the back ones were broken). The clunk went away for a few days, then came back just as bad as it was. I got a third opinion, this pro said it is possibly the cradle mounts...$980, but if it wasn't that... he would look into it being something else. UGH! I'm looking for an alternative, and I will take good advice. I was told on another forum on this site to "check your sway bar endlinks, they commonly wear out, rust through, then clunk on stuff"...
I will have to check that out, but I'm thinking, if it was common, wouldn't mechanics know it?

Suspension noise can sometimes be tricky to diagnose. It may not even be your suspension, but rather your CV shaft. Which do clunk when going from a stopped or turning position. Really, the only way to properly diagnose it, is to have a good understanding of how the suspension works to begin with. Then, get down under the car and start pulling on everything and looking at everything.

Well, according to 3 different mechanics, its not the cv shaft, ball joint, or tie rod and such. If its gonna be an expensive fix, which may not even fix it, I'm going to be forced to sell it which I don't really want to.

the only expensive thing is replacing parts if you dont know what it is. if it only does it once its going to be something like a bushing for the control arms, engine mount, or end links. could be tie rod ends too. that one is easy to figure out just have some one turn the wheel back and forth while you watch for play. any little bit is enough to be a big deal

This clunking happens all the time, everytime. Guaranteed during turns, and acceleration. Once in a great while during a bump, and stopping. If it doesn't happen with one activity, it does with the other...

Sorry, unless anyone of us can physically get under your car and look, we can't say for sure and we would be guessing all day long at what it could be.

That sounds about right. I guess I was hoping for someone who has gone through this before. Thanks to all for any ideas or suggestions.

i meant once, like one knock as opposed to like a playing card in a tire sound

Okay, so you've already had this to three different wrenches and they couldn't tell you what was causing it. My vote goes along with Mike and the constant velocity joints. They boots may still be good and not leaking and I could see a wrench taking a look and figuring - Hey, no leakie not problem here! My $0.o2.

Can be lots of things. Mine does it too. My steering rack and control arm bushing are very worn. In my case, it'* one of these, the rest is new.