There are two longerons that run along the top of the side skins from the firewall into the aft fuselage. They come mostly fully formed and pilot drilled. You do have to induce a permanent 10° bend in the the pieces. The manual tells you were to start the bend. You clamp it in the vice at the bending point and then clamp a board to the firewall end and twist. I had to twist the piece over 130° before it took the permanent bend.
It is shown test fitted in the third picture. The two blocks of wood used for clamping are shown in the last picture. These wood pieces and the piece that goes between the spars were made from hard maple by my son-in-law.
