are you lugging the motor down??? I know you said you are supposed to be in 3rd, and you put in 4th... If the RPMs are real low in a higher gear it will cause the tranny to rattle, it is normal...

 

grumpy 4.8 u answered it thanks man!

 

I have the same problem (A4). It's nothing to do with engine load. I hear it when I give it gas from a dead stop. It rattles quickly for about 2 seconds then quits. It comes and goes. I was thinking it was a heat shield but I have yet to climb under and take a good look. Perhaps a cat (I hope not) but is there anything else under there that anyone can pin-point that would rattle like this?