Dang! There go any possibilities of it being the transfer case :P

Alright, lets break this down a little more...

We've ruled out the bearings in the bellhousing.
We've ruled out the transmission.
Since it makes the noise sitting still, it can't be a driveshaft, rear axle, or brake issue.

Have you checked your accessory belt? A/C compressor? Power steering pump? Alternator? Radiator Fan?

This may sound crazy, but with the engine cold, take the belt off and run the engine for no more than 5 mintues!!! And see if the noise is there.

 

Well, as far as I could see..

The only things that make a whining noise are...

Transmission, P/S Pump, WaterPump, Driveshaft, Alternator, (or the entire pully system), Fan, and Diff...

It cant be the Diff, Driveshaft, and most likely not the Fan, Alt, WP or PS Pump.. (because it sounded more coming from behind) the Transmission was my last bet...lol im going to have to get more clues..

 

I edited my last post too late... go back and re-read it one more time.

I know you said it sounds like the sound is coming from behind the engine, but sounds can travel... or at least thats what I'm convincing myself of cause nothing else is making sense!!!

 

Lol, this may sound a little odd (but all the normal stuff has been ruled out)...

If the truck starts making that noise again, and continues to make it with the truck sitting still in neutral at idle, get under it and take out the slave cylinder and see if it goes away.

 

How do I take it out? Is there an electrical connector or do I have to take off a hose?

What i'll do is, I'll drive it tomorrow and if it keeps making the sound i'll take the belt off.. i think thats the only way to see if it will stop, i think your right! If it doesnt than i'll... go crazy!

 

Here is what I'm thinking right now with my last couple posts...

Either something in the accessory bracket/belt system making the noise.

OR

The slave cylinder is not always allowing the throwout bearing to back all the way off the pressure plate, which would explain why it is a random noise.

So if you can rule out the belt issue, then take out the slave cylinder, and that will insure that the throwout bearing is allowed to retract fully.

You take out the slave cylinder by removing the 2 bolts (or nuts/studs, I cant remember) and pulling it out. Shouldn't take but a couple minutes with a ratchet and socket.

 

Yea that sounds pretty good, i'll do that.. I didnt know I could do that at Idle though I thought it had to be off but cool!

If thats bad, that would explain alot... The weird thing for me is if it was on the pully drive it would be louder or stop for a while after i revved it up.. but it just goes away at higher rpm than comes back around 1200-1500 when its kinda quiet.

I'll try those and let you know if it makes a diff. I really apriciate the help.. my bp is down 50 points haha

 

Haha, no problem! I hope something I said helped!

Get back to us.