Rattling noise from under the hood when stopped under gear (drive)

Thank you. I have searched some forums and found answers pointing to timing chain cassette or clutch. Your thoughts..?

I agree with mastertech. When at a stop and in drive there is a load on the engine making everything loose want to chatter. Heat shields on converter and exhaust manifolds rust out and get loose or spot welds fail causing a chatter

I agree with you. I have a 2006 Xterra 4x4.... It will sometimes vibrate at stops when the engine is cold. When it warms up, it doesn't vibrate. The relevance? I was having major vibration which would get quite loud even when the truck was warming up while in park. I took it to my mechanic hoping it was going to be a simple fix. I sat in the shop for almost an hour and started getting worried about what the bill would be.... Turns out that I had loose shields, loose clamps, and part of the exhaust itself was loose. They removed a few things and tightened up others, but didn't charge me at all because it's my regular mechanic. For those who don't know.... These trucks have some power, as it's a 4.0 V6 and my mechanic told me that he's always tightening shields/exhaust/ parts underneath because the engine vibrates them loose. I's also like to add that in the engine compartment there is the guard on the radiator that covers the fan blades..... For some reason, it will bend/move/shift, and the blades will rub against it causing what seems like an internal engine or underneath sound. Part of the air filter unit runs across the top of it... Put you hand underneath air part, but on top of the blade guard, press down and you will hear the sound stop. I wedged what is like a piece of very firm fire retardant foam between the part of air unit and guard, no more sounds. Again.... My mechanic says the 4.0 is almost like my Harley.... They vibrate and knock stuff loose. I bought the truck new and it vibrated then as well.