Burstner Dinette/Bed Infill Brackets

[fripp]

Does anybody know where you can get the brackets used for the bed infill pieces used to convert the Dinette seats into a bed on some Burstners? It is a brown bracket screwed to the plywood triangular infill base with bent over hook to connect to a bracket on the travelling rear seats.

 

Looking to make my own if possible rather than the £350 cost for the Burstner accessory, as only need for occasional use.