It might be coming from o2 sensors. All tubes have plenty of clearance and not hitting anything.

I hear this is a common problem in our trucks what do yall know?

 

First I have heard of it. Anywhere your headers could be hitting?

 

Nah man I'm always downshifting when messing around with friends and have never heard any rattles of any sort

 

Anytime I had issues with rattling exhausts (as long as they weren't hitting something), I just put a flex coupler in place of some pipe and it will usually keep the resonance down.

 

i have never experienced this issue

 

My bro had this issue with his 07 after installing headers and ORY...the issue was the Y pipe touching the cross member at just the right exhaust note...we wrapped the Y with some header wrap (read that online somewhere) and it stopped the issue...you have duals, so I'm not sure it isnt the same for you, but make sure the piping above the the cross members isn't flexing enough to touch...

 

I have also seen headers hit the heat shield under load.

 

I had a rattle, drove me bat **** crazy for months! Never figured out where it was until I killed my transmission, while removing the exhaust I found one oxygen sensor loose. Hard to believe a loose O2 could make that much noise.

 

The long tube headers have a solid half inch clearance around the frame where it is closest out of the whole exhaust system. The rest of the exhaust is a solid 1+ inch everywhere.

two of my buddies have stock exhaust besides a muffler and the have the same exact rattle as mine.

Its a lil buzz when down shifting from 30-5mph. Kinda like a washer rattling not exhaust tubes hitting metal

I checked all the O2 sensors this morning and they are tight.

THIS IS DRIVING ME CRAZY not finding where the rattle is coming from.
I'm thinking about buying high temp o rings for the O2 sensors and see if the fixes it.

It also is much more noticeable when it gets cold out side.

 

Check your the transmission lines, they could be hitting the exhaust pipe.