The nav antenna came in and I listened to Billy and drill out the revites on the vertical stabilizer fiberglas tip so that I could mount the antenna where I was instructed. Like the commercial says, I should have measured first. The antenna base is 2.5" in diameter and the vertical stabilizer is only 2" wide at the top. Bummer, I hate when that happens. So back to my original location under the fuselage. I made a doubler for the antenna, installed 4 platenuts on the doubler and driller and dimpled the doubler and the fuselage for rivets.