Old Chevy truck tranny question

[nosoup4u]

I bought a 1968 Chevy 2 ton truck at an auction this winter with a 327 engine and 4x2 tranny. It got its first real use this week and I need some help diagnosing a problem. When you are driving and get to top RPM just before you are ready to shift, it makes a loud squeal from the transmission area. Almost sounds like a fan belt squeal but it is coming from below. After you've shift and it is lugging it is quiet. It will also do it at times cruising down the highway empty.  Is this the throw out bearing or something else?

[Nebrfarmr]

I have an old IH that did that.  It was the parking brake band, rubbing on the drum.  My best guess is that above a certain RPM, it would start to vibrate, and rub the drum.  It did it in the upper 3 gears, and only when the engine was wound out.  Fiddling with the adjustment took the squeal away, and left me with just a little funny buzz/rattle, which I can live with as it isn't very loud.

[r3020]

Check the u joints.

[infire]

Your on the right track, you should be able to change the sound alittle with the clutch pedal while it's squealing to confirm throw-out bearing is going out.

[r3020]

The clutch throw out bearing does not turn until you push down on the clutch.