need help with a scrpaing sound

[don_bagz]

hi guys.. well i just got my 240 the other day and it is stock. when i pulled in in my drive way the first time i backed it in and I heard a scraping sound so i pulled out and just parked straight on with an angle (thinking it was scraping). Today I noticed as i was parking on a slightly inclined road the scraping sound came up again.. So i thought to myself, there is no way the exhaust would scrape on a level ground. So i figured it must not be the exhause scraping..

Does anybody have any idea what it could be? Thinking it might be the transmission, but it doesnt always do it. I still have to figure out when it does it. i mean i know it only does it when im in reverse, but, i think if i start steering it will make that sound. it sounds like its coming from the rear side of the car. Any advice would help.. thanx