Drilled the bottom edge of the firewall to the cross beam through the bottom skin. Drilled the aft edge of the bottom skin to the cross beam through the aft skin. Drilled the forward and aft spar tunnel parts to the bottom skin. The rivets on the F12 side panel at the forward and aft side of the spar tunnel probably should be left out of the F12 until after these spar box parts are installed. Because they need to be tilted into position, and when I'd get one side right, the other side would be stuck behind the rivet in the F12 side panel. It's only 3 or 4 rivets per side - at the bottom of the spar opening. Leave these out and getting the spar box in will be easier. Just passed 800 hours logged on the project.
