Anyway - this is what I have understand it is supposed to look like. A front-facing channel spot welded to the front sliding window frame, and a small "lug" welded to the rear one. Here is a space for a loose window channel that goes on after you have inserted the D-window and is screwed to the lug. If you look carefully (not at the picture but at your own Cubs) there is supposed to be a small L-bracket welded to the upper longeron there, preventing the loose channel from falling down into the fuselage sidewall. I saw it on one of the old drawings and it took me ages to understand what it was doing...
I notice now that it IS in fact visible in the picture - a small blue thing under the longeron next to the aft sliding window frame... (This information is for super-entusiasts only... :-)
