Jake is referring to the beam mounts for beam tubes (old style) versus the flat - sided design currently employed. Modernization via the newer beams will require hull mods to the attachment molding/laminating.

Too bad Jim Bauman has retreated to the CA mountainside...that used to be an F 18 HT debacle for awhile... maybe A cats, as well. Jim did a bunch of beam mods for the F 18 HT guys and the Tybee teams back in the day.