I have the Datsun 5 speed in my bugeye and after significant drives, I get a slapping noise when letting off the throttle. It sounds like the shifter hitting the surround and can be felt in the body of the car when putting my hand on it. I took off the surround and drove it....still had it. I looked in the trans tunnel for anything that could be hitting with a flashlight and mirror, and couldn't see anything. Is there something in the trans shifter area that could be worn and cause this? It seems to only do it in 4th and 5th gears.