I was just taking a peak at my transmission and took the little metal cover off where the bell housing meets the engine and this little pin was just hanging out in there. No idea where it goes but it's pretty chewed up.

 

Looks like a bolt that holds the flywheel to the torque converter. You may wanna check to see if one is missing. theyre kinda important.

 

The head on that says converter bolt. The slots are evident. You gotta replace that, stat!

 

I would have called it a bolt that bolts the flexplate to the crankshaft...same slotted head, but obviously both important