bushes

Hey Everyone.

Just a quick question, I looked under the back of my car to investigate the clunk that sounds whenever i hit a small bump. What i found disturbed me havung just had one of my rear callipers replaced. firstly, a groove about 2-3mm deep and about 5mm wide(radial direction) around the rotor with the new calliper.... secondly and more disturbing, i found that the sway bar shackle mounts have no bushes in them... does anyone know the size or part no of these bushes( or good aftermarket replacements). it seems easy enough to replace them one at a time just buy jacking and removing the wheel??

Also, not sure about the US models but what is the big plastic thing above the fuel tank in the 3litre. the sorta rectangular black thing. emissions component?? i think one of the hoses may be leaking cuz there is a fuel smell in the boot and back seat sometimes.