whats that noise?

I have noticed lately when i drive over rough roads there is a noise like im hauling loose lumber under the car. I have replaced engine , tranny, and the circular rubber mounts on the differental but i still hear the same noise from under the car. the rest of the mountings are stock as is the suspension. the car has 110.000 miles.

Your motor and trans mounts would have been my first guess, but they are new, so I'm not sure. I would think you can rule out "Upper control arm bushings" as that is what are junk on my SC. They make a scrunching pop can sound over bumps. Maybe bad shocks or the rubber isolator bushings?

Maybe your front and/or rear sway bar links. Check them out. If the rubber bushings are gone, thats it. If not, check out every rubber bushing in the suspension, front and back. Mine are bad and your sound describes my same sound. Take care.

Lower shock bushings

I had a rattle/clunking in the rear of my SC when I bought it. It ended up being the passenger side lower shock bushing. I replaced both upper and lower shock bushings with the MN12Performance poly shock mount kit. Now I can hear all of the other creaks and clunks of my rear suspension.
DOH!
Bill

The sway bar end links can look just fine, but cause lots of racket. Their noise tends to be an intermittent "bump bump bump" noise. Try to twist the link with your hand. If you can move it with one hand, it's probably shot.