I'm guessing its an implrtant piece otherwise it wouldnt be there....but looking at the diagram I cant see what it does. Could someone enlighten me?

 

I would assume it spaces out the torque converter or it helps keep things aligned if there is a recess for it.

 

I recall the automatic bolts are shorter than the manual bolts. Thinking about that a bit. I suspect the extra ring with the flex plate may be a spacer for the shorter bolts to prevent them from bottoming out and giving a false torque when tightening.

If this is the case, your main 12 point flex plate bolts may loosen up over time causing you grief and possible damage to the flex plate.

 

Thanks for the replies....I went ahead and reinstalled the washer just in case. What a bummer though, I was literally about to put fluids back in the car when I found the thing hiding under the exhaust manifold heat shield. Had to take evrything back apart, axles, shifter cable, yada yada...anyway, it's done now. thanks a lot.

 

Rough, but better to know you did it the right way, rather than worry!