Not an entirely awkward suggestion there.

Noises and sounds are easily conducted throughout the vehicle and all its metal structures. Enough experience of people, including myself, who experienced a rattling sound from near the flex plate, coming from an entirely different cause.
I can remember being on the verge of pulling the flexplate inspection plate off to find loose bolts, so much was I convinced it had to be that, because the noise seemed to come from there. Turned out to be 1-2 pulleys all the way in the front..

Not saying it is, just keep possibilities open until you found the cause.