my 88 4runner v6 started making this really loud noise from what feels like the left front wheel well. i can actually feel it vibrate at my feet. as soon as i put the clutch in, it stops. when i release the clutch its gone. only happens in 4X4. any ideas? oh ya and merry christmas.

 

Some ideas...

Manual hub not engaging/disengaging properly.
Front d-side wheel bearing loose.
Front d-shaft U-joint going bad.