I think its going to be really hard for me to explain but i'll try my best.

It really sounds like a bearing in one of the pullies is going out. but it ONLY happens at really high throttle and i can't hear anything lower.

it just sounds like its grinding kinda high pitched, then once i let off the gas, it stops after a second.

i'd say at least 85% throttle or higher it happens, its never happened below that.

Any ideas?

i'd try to get a video, but i think my exhaust would cover it up since i only have my cell phone to take it with.

 

Are you running an aftermarket fan with larger/more blades than the original ?
Too large of a fan and /or any obstruction to the incoming airflow could make the fan stall at high speeds.
This would cause the belt to slip and sound like a high pitched bearing failure.
For a short time , remove the fan belt and see if the noise goes away.

 

I'm running the stock 5.0 fan but the shroud is a 3.0 that i made to fit. that could be it, maybe i'll call around and try to find a stock 5.0 shroud.

The only time i've been able to reproduce the sound is when i'm flooring it and i'm at least 40 mph or higher.

 

With the engine cold , you should be able to run it for five or so minute without the belt.
That will narrow down if the problem is internal or one of the driven accessories.

 

idk if it would do it when the motor is cold.

plus i'd REALLY not like to floor it without the truck up to temp.