That was the noise I had. It went away when the clutch was depressed or it changed sound. The bearings are the culprit which requires a rebuild or replacement.
DOCTORBILL, I do the same thing when I drive. I listen to the lifters and try to focus in on other sounds coming from the engine and basically "waiting for something to break", but after a while, you learn to install a nice stereo and forget about all the little noises. When the noises get loud enough to bother you (like the trans on yours now) then it's time to worry
