check to see the top of the rear muffler isn't touching the body near the rear bumper, there's a rubber cushion that is there to prevent that. I've seen a exhaust line that was bent up higher than it should and made a grumbling noise where it rubbed against the chassis.
Also an odd noise can come from a fuel sensor inside the fuel tank that lost its cover. That is usually a noise that happens when cornering. don't ask me how I know what this sounds like !
(and I hope that didn't happen to you!)