Chevy & GMC Vans

my 2001 astro recently developed a chattering under the driver side whenever I hit bumps, took it to my mechanic and he can't find the source. a few months later whenever i make a right hand turn, it squeeks, not the wheel turning itself, but it seems to be the pressure of the van leaning to the left during the turn that makes it happen. a buddy suggested a rotor as the issue, but since i don't know much about them myself, I don't know where to start.

A month and no one answered?

Ok I'll take a stab at it. I'm thinking bushing, maybe control arm or body mount. A spring possibly?
Grab a can of WD40 and go to a place where you can cause the squeak to happen every time, a favorite bump perhaps. Make the squeak happen then saturate one bushing and try the squeak again. Rinse and repeat until you try to squeak and find it gone. That will be the offending part.

is your '01 an AWD ?

My son's '91 had some sub frame bolts get loose. It made a noise.

Possible end link snapped?