You may be right, davopam.
My GB plans and manual don't show the firewall being notched for upper stringers, nor the "tabs" on the fuselage sides protruding a little forward beyond the firewall, like in the pictures above.
I bet the previous Seagull owner re-covered it and bought a set of GB decals.
Last edited by Outrider6; 12-07-2022 at 11:22 AM.