Clicking noise after replacing the transmission?

Is the torque converter tight? Also, could it be an exhaust leak? Can you please shoot a quick video with your phone so I can hear the noise? That way I can tell for sure what's going on. You can upload it here with your response. Please let me know if it gets louder if you rev the engine are more silent?

Thanks for the video, it helps. Yep, it sounds like the flex plate is cracked or the converter is loose. Also, does the transmission work okay. You may have not gotten the torque converter installed completely which will make noises like that, but at the same time the transmission will not work. It is not an exhaust leak, let me know what you find you may need to remove the transmission again.