Funny noises - could be guibo?

I'm having a a audible thump noise coming from below the shifter while the engine is cold . I can feel something hitting the tranny tunnel from underneath ,but when the engine warms up the funny idle goes away and the thump goes away. The noise is also there at times but sounds different like thudering with minimum vibration. I inspect the guibo ,and it looks normal with no crack. My last thought is it the tranny mount ?

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: Replacing the 3-Series Driveshaft Guibo / Flex Disc

[Wayne 962]

I would normally agree that it sounds like a dissolving guibo. But, these tend to stay noisy when the car is warm or cold. The fact that the noise disappears when it's warm is suspect to me. It may be some type of problem with the transmission, and it just appears like something is hitting the top of the tunnel. If possible, I would put the car up on a lift / rack and see if you can run it cold and look at it underneath while it's making the noise. That might give you some additional clues.

- Wayne