'97 Taco V6 4X4 5 speed R150F whining noise in 5th gear

That sounds like a throw out bearing to me. I have the same exact issue and have just been living with it for a couple years. I do plan to fix it. New throw out bearing only runs about $40 last I checked, but unfortunately requires dropping the trans to replace

Search YouTube for "Tacoma Throw Out Bearing Noise" and you'll be able to tell if that's the same thing you're experiencing.

 

actually the throw out bearing is Also chattering away for the past couple of months LoL... but not at all funny since it was just replaced ~5 months ago
But! that noise is Gone with just a slight depress on the pedal, pedal might need to be adjusted yet again?

i can even hear the throwout bearing making noise in 1st and 2nd gear in motion if the RPMs are not high and/or other traffic noises to drown it out

the mentioned concerning noise only goes away with full pedal down
which could be the pilot bearing? IDK!?
i have found the test for pilot bearing somewhere online need to find it again

dropping the trans (again) is 6 to 9 shop hours

 

Hmm, that it is interesting. Mine is noticeable at idle only in neutral, but just a slight bit of pressure on the clutch pedal will stop the noise. Not sure if your symptoms indicate other issues like a pilot bearing too or poorly adjusted pedal. Maybe @gearcruncher could weigh in

 

i still don't know What exactly stops rotating in there when the pedal is pushed all the way in?

input shaft & bearing stop rotating or does it always rotate with the flywheel?
the pedal did have to get re-adjusted because it would always flop back right near the end of the return stroke as soon as i took the foot off it would pop back and never did that before, it was always nice and smooth travel LoL

 

Preach! Hehe. When it's good it's great. And it's still good when it isn't great.