Used my plexiglass panel to align the GTN tray and set the spacing of the vertical support angles. Clamped everything I'm place and drilled a couple #40 holes through nut plate holes in the bottom brace. Cleco'd that in place and drilled the #19 holes through the plexiglass and into the vertical angles. Removed the top skin and drilled the top holes from the vertical supports into the top panel flanges. A little tricky, but got it lined up.

Got the GTN cutout marked on the subpanel and cut it with the oscillating tool.

I thought the autopilot head was going to fit below the center forward rib, but it doesn't. Decide to trim a small piece off the corner of the brace and reinforced it with a short piece of angle.