I just had this same noise. While I was fixing a few leaks I noticed the cross brace mounted to the tranny had one bolt missing. the brace was hanging by one bolt. Anyway I went to Autozone and got two new bolts and replaced both no more noise. This may be the same problem hope it is that easy for you. Cost me about 2.00 to fix the problem. I also have an auto tranny by the way.