Ok, a little more backstory: I had what sounds like a similar knock especially noticeable at or near idle. I had Ben & Joe at Slee listen to it, Robbie and a couple of my regular LC travel buddies and everyone concurred it was probably the flex plate. Well, it wasn't. The knock was still there after installing the new flex plate.
But, unexplainably, the noise went away and the engine just purrs so smoothly and quietly today.
well then it sounds like we had similar situation because the the noise is still gone and car runs just as smooth as can be now.