This is the Flex Plate in my 1956 Mercury Monterey with the 312 V8 Engine. A few years back, when idling, there was a noise coming from the transmission area that we could not detect where it was coming from. We pulled the Engine and noticed that the riveted "fingers" on one side of this Flex Plate were loose, and that was what was causing this noise. Took the Flex Plate to an Engineer and he tightened them up and there is no noise there now. Problem solved.