I used a unibit to drill holes in the GPS antenna mounting plate for the antenna connections so I could get the pucks to sit down flat. Then I laid out and drilled #19 holes to mount both pucks. For now, I plan to use nuts to hold the screws—maybe in the future I’ll add nutplates, but nuts for now. I drilled the angle, backing plate and f/w up to 1/8” followed by a #30 reamer. Drilled and c/s for nutplates. Cleaned up all the parts and shot a coat of primer. While drying, I lightly sanded the inside of the lower cowling and shot a coat of high temp white--it will probably need a second coat. It does not have the finish as an exterior piece of glass, but good enough. Some of it will be covered with foil at a later time. Primer was dry on the antenna shelf pieces, so I squeezed rivets to secure the nutplates. Next, I used the gun to drive rivets that attach the angle and backing plate together with the f/w sandwiched in between. Due to some lack of planning, I had to turn the end rivets with factory head on inside—could not get a rivet set on from the front due to the proximity of nutplates—no big deal. I installed the antenna pucks and secured the GPS mount. I believe I have enough room to mount one other antenna if needed in the future. Next up—route and attach the antenna cables.