Tranny Whining Noise

I own a 1997 Mazda B2300 2.3L pickup, There is a loud whinning sound coming from what I belive is the throwout bearings, it can be heard in neutral and while driving, how can I be sure this is it? I have no other problems with it, shifts fine too.

I don't have experience working on manual transmissions, but how hard is it to replace the throwout bearings if needed?

Or what else could it be?

Any Idea anyone?

could be a release bearing, could be an input shaft bearing. it is really hard to say without hearing it. both require removal of the trans. the release bearing is built into the slave cylinder. and the input shaft bearing would require trans dissassembly