Vibrating/Rattling Sound

Hello, I have an extremely loud noise coming from my transmission. If I clutch in or have the car in neutral, the noise goes away. My input shaft bearing is bad but I don’t know if it would be the cause for this sound.

It almost sounds like something is vibrating like crazy and when I compression brake, it sounds like I have straight cut gears (which should be the ISB).

Here’s an audio clip:

http://vocaroo.com/i/s0vURHFRVBIK

What’s very interesting is that it doesn’t start making that sound until you start moving. Sometimes it occurs at 1500 RPMs, sometimes at 2500, but if you give it some gas, you can take it up to 4000 (haven’t tried any higher because when the sound starts, it sounds like the car is going to explode). 1st to 3rd is pretty loud but the sound starts to quiet down in 4th and is not very audible (if at all) in 5th. Whatever it is, it is RPM dependent but the noise is not; once it starts rattling, the pitch does not change.

I have the car on jack stands and I can go through the gears just fine without any noise. I’m guessing this has something to do with no load being on the drivetrain but since the transmission is still spinning, could it still be the culprit?

Thanks in advance for any help!

THat is a vibrating heat shield.
It will cause no harm, but will drive you crazy.

If you can get it up on jack stands, you can crawl under and find the loose one. Self tapping screws and an electric drill will enable you to secure the heat shield back in place, but use caution in where you drill.
I know someone who put a screw right into his gas tank because he didn’t pay attention.

Yosemite