Muffler rattle in low gears?

Since I have had my truck, a total of almost 2 months, everyone in a while I notice a quite audible rattle coming from the rear passenger side of the truck. This only happens when i am either gearing down, or going up from 1 to 2nd or 2nd to 3rd. It may happen in the higher gears although I cannot hear it as the engine is probably loud enough to muffle the sound. Has anyone else heard about this? I am taking the truck to toyota for the first oil change, so I can get a chance to talk with the mechanics about what problems they have seen and what toyota will fix. The service department always seems more helpful than a salesman. This problem doesnt happen all the time, maybe twice a week but when it happens it happens over and over throughout that day. Id like to have some ammo when i attack the dealer tomorrow so any info would be greatly appreciated.

Thanks

 

I get the same rattle. I thought it was a muffler or pipe tattling on the frame. My svc guy says its to far from the frame. He;s heard it and is going to investigate it at my first oil change. I ususally hear it in 2nd or 3rd at low rpm and sometimes starting off in reverse
I'll keep you posted.

 

im going in for my oil change tomorrow so ill let you know how i make out tomorrow night.

 

Looking forward to your results. Whats ur weather on the west coast...we're -2C right now looking at -12C by AM

later

 

JHodge Its to far forward to be a loose spare. Its a real 'tinny' sound. On TNation someone mentioned a cold air intake, but its plastic. On my truck it seems to be right under the pasenger seat. As with any rattle it could be originating from anywhere.

 

So what did you find out about the sound? Was it the thin heat shield vibrating against the exhaust pipe?

 

Dutch....That makes sense I'll check it out

 

mine was actually some thin heat shield hitting the driveshaft boot. The weather here this morn was about -5 and got up to around 9 celcius later in the afternoon.

 

Thx Cory and Dutch....I have it checked. It was -12c with wind chill -22c in NS this morning. Its now -4 at suppertime

 

cat. converter heat shield maybe? That was the cause on a friends `86.

 

Seems in my case its the fender end of the cold air intake. A new one is on order.I recreated the noise, my tech held the plastic intake and I could not get the sound to comeback