HI:

I just got a Busch Pressman C (2-1/4x3-1/4) missing a back.

I had a back already, waiting for a project.

What I'm not sure of is what may be missing as the belows looks like a mounting flange was removed from the rear of the bellows so the back end is just unfolded.

I'm sure I can rig up something simple and functional but it would be nice if someone could describe what used to be there.

Thank you.