The two inboard most stiffeners are easy to clamp in place and they locate themselves. I had to notch the forward end of the two stiffeners to clear an angle on the firewall. The lengths are just right with no trimming and I was a little worried about edge margin on the ends.
I drew centerlines on the back, but could not see them thru the holes of the two center stiffeners when they were clamped in position. So I put red dots on them thru the holes and took them off and checked. The red dots are close to center but well within edge margin limits so I drilled them.
