The 121mm S.A. is a curiosity in that it appears in a housing or in the
normal form.
I have seen four examples on ebay, two housed and two normal. One of the
housed examples was also mounted in a Plaubel plate like mine.
My interest in dismantling the lens was in case the thing would fit into the
bellows of a Pacemaker Graphic.
The Primary reason for its acquisition is for my Linhof.