Ive been having this rattle noise in the tranny for a few months now and i can figure out what it is.When im in 1-3 gears at lower RPMs (1-4k) i get this rattle noise in the tranny when i start rolling from a stop.It doesnt do it in neutral and when i push the clutch in it goes away.Anyone have any ideas?

 

possibly your throw out bearing???

 

Update.....

I jacked the car up and put it on jack stands to try to create the noise while a friend listened. After going through 1-4 gears it wouldnt do the noise.So i looked under the car and noticed that my passenger side castle nut behind the rotor was 2 threads from falling off and neither side had the cotter pin in it.I tightened up the nut and got cotter pins and ill try driving it tomorrow,hopfully this was the problem