http://ac.unpatented.com/pics/trans/oldtransmission.jpg
Maybe you can read this?
That pic looks pretty much like a B2B, same shape-size and location as what I had seen. Just yellow instead of aluminum.
I see it is part way out. My guess would be that the metal shaving are jammed in between the piston flange and the walls around it. If you do not intend to save the B2B you might use a pipe wrench to spin it around and get it out. Maybe use a rag to protect it from the wrench. There is a dogbone behind the B2B that is pushed by the B2B into the band. The B2B is supposed to slide freely in the cylinder there. The band keeps tension on the dogbone,which in turn pushes the B2B into the round cover.
http://ac.unpatented.com/pics/trans/b2bpiston3.jpg