High pitched whine at high rpm

[Lothsahn]

My 1996 GTX started making a faint high pitched whine above 6000 RPM. Any idea what it could be?

I did just replace the impeller a year ago, but I normally don't drive fast (35mph speed limit) so I wouldn't have heard the problem. If the hub bearings are bad, what symptoms would I experience?

 

[POPPS]

It could be a pump bearing gone bad,,or a gouged prop,,,or a scored wear ring,,,or the pto deal is leaking,,,