40-41 pickup seat ?'s

[hotrodA]

Back again about my new to me 41 pickup. Tried multiple searches, no luck.

The newly upholstered seat has me stumped. The support is good and installed.
The wood cushion base is missing. I'll make it from plywood.

The bottom cushion has a flat steel pivoted arm about 4" long attached at the rear on each side. What does this go to?

The back rest cushion has halves of two box hinges riveted to the edge of the frame. Where and to what do these attach?

Anyone have pics that they can post of this?

Thanks!