Noisy powertrain

I bought my 2003 GT Convertible new. As I was driving it when new I noticed a clacking sound coming from underneath the car. It sounds as though there is too much play in the gears. You can usually hear it when shifting especially after just letting off the clutch and hitting the gas. But going slowly - making a right hand turn. If I jump on it I do not hear the sound. It sounds like hell and drives me up a wall. I was told by the dealer who "assured" me ALL the cars they had on the lot back then did the same thing. My question is has anybody else noticed this sound and figured out what it is? I am kind of hoping it is the ring/pinion set as I am getting ready to install 4.10s and would be happy if this sound STOPS!

Thanks for taking the time to reply. I figured it was a universal problem and it is indeed frustrating. The reason I asked was because there was a TSB out on the Cobra with a similar problem. Except for this noise and the delaminating of the paint on my hood (if one more person tells me I drive too fast!) - which is also covered in a TSB but mine started after the warranty expired and I am screwed. I actually think my MGK shifter quieted it down some although I am probably living in Fantasyland.