Transmission rattle ('02 6sp)

Last night I test drove a very nice '02 Camaro SS with 6400 miles on the clock. It had a 6 spd, and I noticed a very audible rattle in the transmission, mostly when shifting into 3rd or 4th gear. Any ideas what this could be?

I am a novice at shifting, so it could be my fault. If it is my fault, what did I do to cause it?

Could be the throw out bearing, but are you sure its coming from the transmission? Could be the exhaust rattleling when the rpm's drop down before shifting.

All T56's rattle when you lug the engine (<700rpm). I don't know if that would be what you heard, but it's normal and not harmful. Even a brand new Z06 or Viper will do it.

If you weren't lugging it, then I'd suggest that the exhaust could be the culprit as well.