99 z-71 rattling

I have a 99 Silverado Z-71 ext cab w/5.3, aftermarket exhaust and im getting a metallic rattle coming from the mid to rear section of the truck and i cant find out where it is. I thought is was something in the y-pipe, i was wrong. any suggestions greatly appreciated.

did you check your heat shields? mine was doing this on my 02, just a thin metal sheet bewteen exhaust and floor. i had to bend mine down just a litttle so it did not touch the floor.

tried the heat shields and nothing, truck still rattles. started taking the exhaust apart and snapped both bolts on the y pipe. im going to take it to a shop and have the exhaust fixed and see if they can find the source.

tried the heat shields and nothing, truck still rattles. started taking the exhaust apart and snapped both bolts on the y pipe. im going to take it to a shop and have the exhaust fixed and see if they can find the source.

it could be the cats, inside they can rattle, may need replaced.

well i went and had the truck looked at, and it turns out all the rattling is coming from the cats, so im going to have them replaced and see how that goes. thanks for all the suggestions

well no luck with the cats, got those replaced today and the truck is still making the ratteling noise, my next thing is the O2 sensor, its making some noise, and if that dont work im not sure what else, still open for suggestions.

i noticed the same sound coming from the same area yesterday and today as well. mine doesnt rattle all the time, just usually once and a while.

well no luck with the cats, got those replaced today and the truck is still making the ratteling noise, my next thing is the O2 sensor, its making some noise, and if that dont work im not sure what else, still open for suggestions.

There really isn't anything that can rattle with an O2 sensor. It is simply a probe that screws into the exhaust pipe. It can not even unscrew itself, because of the electrical connection. I would guess your problem is elsewhere.

well im going to try and clarify a little more to see what else you guys think, the truck only make the noise when i go over bumps ie: bumpy road, speed bumps stuff like that. but its only when the rear wheels go over them and the noise sounds like rattling or metal bouncing inside something, thats what made me think exhaust for starters. Then when i had the cats replaced the shop i took the truck to hit the pipe and the o2 sensor was making noise, which does baffle me. the noise is coming from the front of the truck and i would say no further back than mid cab (i have and ext cab). so im still open for suggestions. Im just getting really frustrated with this. oh and the truck needs new shocks if anyone thinks that might make a diff. Thanks Ya'll

well if the cats were rattling it could be that a piece of the cat made its way into the mufflers i had that happen ti me when my cat broke