It's a Dura Ace 7900 BB. Cranks are FSA Gossamer. Didn't see any washers when I took the cranks off, but it seems to be working okay. I assume the washer is just to keep junk out of the BB, and doesn't have any mechanical purpose.

Turned out my pedal was making the creaking noise, not the BB. Now I have a spare BB. Anyway, it was a fun learning experience. I heard the Mega Exo BB isn't very good anyway.