mine started out as a vibration during deceleration from about 3000 rpm down to about 2500 rpm, more noticable when coasting down hills with your foot off the gas, vibration comes, just touch the gas or apply the brakes, vibration goes away.
The vibration slowly turned into a rattle/ grating like sound, same sound as if one of the aluminium heat shields above the exhaust was loose (checked that too). Has not gotten any worse over the last year (still a loud rattle), I don't know if its audible from outside the car, but if you are coasting down a hill with the windows down, you can hear the sound bounce off any gutters or islands in the middle of the road so I'm assuming so.
Still yet to pull my box and right angle drive apart to have a look. So little time, so many bloody cars to fix.
Weird that yours came only after your incident. Maybe the impact has screwed something up in the rear. Check the rear wheel bearings for any play or slop.
