Replacing parts due to clutch chatter?

John, do you feel the click in the shifter handle when you shift? If not, it is probably not the shifter. Do you feel it in the floor, or column, then its something hitting the body. Try to identify what else moves in that process. Are the bell housing bolts properly tightened? Check the yoke and U-joint caps. Motor and trans mounts. Think about what loads, and unloads when torque is applied to the drive train. Could the exhaust be hitting something? Good luck, I don't envy you.