someone please let me know what this sounds like to you,,,my car is making A clanking sort of noise(like if a bolt were loose somewhere inside something),and it only happens when the car is in gear(drive,reverse)especially when i give it some gas,it also sounds as though its coming from the passenger side undercarriage.what could it be????

 

Its hard to say from the way you describe it. Are you sure its not an exhaust rattle? I had one once that sounded terrible, and yes, it only did it while the car was in gear.

Is there any way you could post a sound clip?

 

I would say check the bolts for your cat. I had one of them come loose and it made an annoying rattle. Go under the car and bang on the cat. You should hear the rattle if that's where it's coming from.