Same thing happened to my Jeep. It sounds like one of the torque convertor bolts are hitting the transmission inspection plate. It's annoying, mine doesn't go away, doesn't matter if hot or cold. I bent that plate to a position so the noise isn't as loud, though. And this happened to mine after I replaced the engine, too.
PSA - It would be nice if people made an attempt while typing to discuss their problems or opinions instead of one long sentence with no punctuation. Maybe I'm cynical, but that really pisses me off. Rant over.
"It's like saying I had a car I got that was painted by the previous owner. I had an accident so painting a car is unsafe." - cykaaro