The F-705 bulkhead sits behind the seat - it serves as a seatback rest, and more importantly, attaches to the rear wing spars besides strengthening the cockpit. Did some alum. bar fabricating. The F-705B bar was already pre-bent, which is new compared to older kits looking at others builders' websites. Spacer made, all parts drilled in assembly to the F-705A bulkhead. NExt, the seatbelt anchors were clamped and drilled. I used alum scrap to create the 3/16" shim spacer, clamped with cleco clamps, then clamped to the bulkhead and drilled one side. I attached a bolt, then drilled the other side. Worked well (pic 3).