transmission noise???
 

My '04 Civic EX is still operating like new with 107000 - however she's starting to make a random rattle when I'm moving slow or sitting at stop lights. Pretty sure it's coming from the transmission - no rattle when i'm in neutral or park. I found my trans fluid is low, but I cannot find any leaks. Also not sure how much fluid i should put in.

Any suggestions? Thanks a ton!