Had this issue with my TJ muffler heat shield. Fixed with a new cat-back (and gained an exhaust rattle, made a MUCH more annoying sound)

 

Check the muffler heat shield. I search everywhere and finally saw that the muffler heat shield was just a little bit loose and would rattle at 3000-3500 rpm. It's an 11 mm nut and can be reached with the muffler still on.

 

Add me the rattle noise club. My 07 Sahara just developed this issue a few days ago. I wonder if it'll go away once the temperature drops. I noticed it began as soon as the temp hit in the 90's!

 

My 08 Rubicon has a similar rattle coming from infront of the driver's footwell. I'll look into the heat shield as soon as I'm off work. Thanks for this post!

 

Mine rattled also. Although it sounded like the rattle was coming from the driver's side, I found it to be a one of the spot welds holding the heat shield on the exhaust crossing beneath the transmission under the passenger-side floorboard . At certain RPMs, it would cause an annoying rattle against the exhaust. I bent the shield out away from the pipe where the rattle was which helped for awhile, but it stills rattles occasionally. I will just get someone to re-weld it when I get a chance, or I will clamp it.

 

I shoulda never posted on this thread, now I got g'damn rattle I can't locate, only does it when I get down on it a bit, sometimes not as much. My heat shields are a good ways away from the exhaust under neath cause of the body lift. Sometime its in the middle, sometimes driver side rear I'm gonna try to look real close at the crossover pipe, cause it's gotta shield too. Dammit. If I shift into neutral while moving it'll do it, but it won't do it sitting still.

 

I had an annoying rattle for a while. It ended up being a loose clamp on the exhaust pipes under the driver side seat. there is a clamp where the pipes go from two to one and i tightened it and the rattle went away. check yours I'm willing to bet thats some of your guys problem.

 

Found mine, as someone else had posted, it was a broken weld on the heat shield on the crossover pipe. I was starting to think it was my tranny
Finally found it after hunting for it over several days. One tiny weld and it vibrated like a bitch. I just took a screwdriver and bent the shield away from the pipe.

 

my rattle sounds like it is right under me. it occurs when i'm bogged down....like when i start out in 2nd but should have started out in first... or cruising slowly in a parking lot in 2nd.

i had my jeep at the dealership for another minor repair (under warranty) and described my problem. here's a good one: they said it was the shift knob that was rattling, and they replaced it. yeah.... THAT helped. it was free under warranty, so i took the new knob... but wtf. that place is useless.

 

Add me to the list as well. Just spent the last 30 min underneath and can't find anything loose. I'm sure it's the heat shield. Same as WaIIbanger. Normally starts rattling when I am creeping through the parking lot at low rpm.