Drilled, deburred, riveted F-981 attach plate to the front spar after adjusting vert stab. Here is where I recovered an error. I accidently misread a measurement, and found that the rear spar was bolted 1/4" too low on the rear fuselage. The front spar attach plate came down all the way to the horiz stab spar, but there was difficulty keeping the rear spar and the rudder hinge brackets aligned. I built a shim from scrap aluminum and sandwiched it between the F-981 plate and spar. This left the rudder hinges perfectly lined up.