Started working on attaching the horizontal stabilizer to the fuselage. The first thing I did was to establish the squareness of the horizontal stabilazer to the fuselage. I measured from the uppr corners of the firewall to the end forward corner of the HS. I did this at least 5-6 times on both side of the HS and established a distance of about 153 1/16". While doing this I clamped the reat spar of the HS to the two attachemnt bars.