Drilled the #12 and 1/4″ holes through the vertical stabiliser into the rear bulkhead. Vans says it is critical to ensure that these are drilled perpendicular to the bulkhead. For the #12 holes we used a bucking bar clamped to the bulkhead and a cleco to align the drill. I had “sighting” help so I ensured lateral alignment and H advised on horizontal guidance. Not so easy for the 1/4″ holes and there is a lot of metal to drill through. We used the rudder brackets for alignment and added an AN4-6A bolt as we drilled as per the instructions. I had purchased some 1/4-28 UNF wing nuts to make this task as easy as possible. The bolts are nice and snug so hopefully correct!