Weird noise any idea what it is?

ok when my RPMs get up to about 4000 rpms in any gear and even when revved in nuetrual I hear this sound that is like something spinning out its very weird and it does almost sound like metal but once I get past 4250 rpms it goes away but if I let off the gas as it goes back down to the 4000 mark it makes the sound until the rpms go below 3500 the noise is in the 3500-4250 rpm range my dad thinks it might be the throughout bearing but anyways any ideas would help.

I searched the forum and couldnt find anything.

Anybody?

possibly throwout bearing, could be a pulley, or going-bad pump...

water pump and oil pump are new throughout bearing was on the JY tranny i got so I am willing to believe throwout bearing.. PS pump is old could be that but I havnt had any problems with it. all engine internals are new so I really doubt its the main bearings or anything like that.

I just really wanna make sure its not anything thats gonna screw up my rebuilt engine.