noise when i slow down

If any one can help with this one it would be greatly appriciated. This noise only happends when I slow down comeing up to lights. Its a rattle kinda like a exhaust pipe banging but i went under the car and shook it as hard as i could and didn't here it. Could it be the U joint or something in my rear end. Or possible a cat gone bad. I have no idea what it could be. Thank you in advance......

maybe the tires are not aligned?

I think its in the rearend. Someone can correct me if I'm wrong but I beleive we have a Torsen unit and they are prone to rattling when there is no force applied on it but the car is moving (ie coasting to a stop.) Maybe someone knows for sure?

does that mean the torsen unit is bad and if so how much $?

It sounds like it's the cats. If they are bad, you'll get an SES light. That's what happened when both of my cats went bad. Common for 2000 f-bodies. Keep an eye on it . Pay attention to any changes. Are you feeling any vibrations? If so, where?

I get a lot of vibration but thats from the loud mouth. no other bad vibrations just a constant knocking sound. Was checking somethings out and found that one of the bolts for my lug nut on the driver rear was broke or striped trying to fix that to see if that is the problem. Also when I shake the rim it makes the same noise when i am parked.....

I notice a clicking sound when slowing down to a stop. Just had my Torsen diff rebuilt due to bad pinion alignment. I was told sound is normal but I am not sure what the source of the noise is.

The Torsen noise comes from the clutch packs "floating" in the housing when they are moving, but not under load (i.e. not acellerating)

The Torsen noise usually is louder and more noticable when making a slow left turn, expecially a decellerating left turn.

I went round and round with 2 local dealers, GM corporate and Torsen directly regarding this noise. They assured me that it was normal and wasn't hurting the car. I'm glad that car got wrecked and I got into a new WS6 with zero noise from the rear end.