Rattling In front end only while braking

Okay, so i have an 07 DCLB with the V6, 4x4 auto tranny. It has about 102k on it, bought it at 100k, i am the third owner. it was working fine when i bought it, no rattles, vibes or anything. recently, just started yesterday, i have got a rattle occurring in the front of the truck, only while braking. doesn't matter how much pedal pressure, and doesn't do it all the time, but it happens frequently. My dad drove the truck to work today and he hears it too. any ideas on where to start looking? i will be taking a look tonight and see if i can find anything loose.

 

I know thats not allot to go on, but what are some things that commonly come loose? im just looking for a place to start. i had a look under the truck and there's no leaks or anything.

 

Your brakes are warped

 

the pads or rotors or both? as for as i know the truck still has original rotors and pads on it.

 

Get new rotors. And pads if they're below 50ish%

 

Yep, rotors for sure and pads since they have high mileage

 

Okay, I'll have to check tomorrow, it's dark here and I don't think the neighbors will appreciate me banging around at 1am

 

Okay, the rattle isnt in the brakes themselves. i had a mechanic look over the front brake system and its fine, no warping in the brakes. After driving around for about an hour or so, i am 90% sure the rattle is in the engine compartment somewhere. i would just forget about it but the mechanically inclined part of me says something isnt right, and i want to get this fixed before something expensive breaks

 

Update: it started doing the rattle again, only this time it kept doing it long enough for me to figure out what it was. turns out whenever my truck kicks into high idle the drivers side cat converter heat shield rattles like crazy, i think one of the welds broke on it. it was super loud an i noticed it as i was looking around under the truck.