This is a tough one for me.

Right now I've got a sound issue. I know what valve rattle from flat
lifters sounds like. I know what a bad CV sounds like with it's classic
knock-knock-knock in a tight turn, and the whine of the PS pump when the
wheel is at the stops or the pump is bad. I know the sound of the
throw-out bearing when it's giving up the ghost. But I've got a
transmission/drive train related sound that is bugging me.

Imagine the day's of bicycles when kids used to use a clothes pin and
pin a playing card or piece of cardbosrd on to the bike so the paper
would run against a spoke t make motor bike sound. At dead slow - the
card would go "pop-pop-pop-pop_  as one went faster -it changed to a
higher faster pitch like popopopopopopop and even faster it was just a
continuous higher pitched snarl.

At speed, it's loud enough to drown the rumble of the engine. If I push
in the clutch - the sound instantly disappears and all I hear is road
noise - let the clutch out - and there it is again.. If I put it in
neutral and let the clutch out - it goes away. Back in gear - there it
is again!!

I'm concerned that this is the beginning of something big - like pilot
bearing - maybe even throwout bearing. I would like to fix this rather
than wait until something really big breaks.

Any ideas will be appreciated!!

John